By
From the * Department of Anatomy II, and the Department of Surgery II, Kumamoto University
School of Medicine, Kumamoto 860, Japan
The migration pathways for dendritic cells (DC) from the blood are not yet completely resolved. In our previous study, a selective recruitment of DC progenitors from the blood to the liver was suggested. To clarify the role of the hepatic sinusoids in the migration of blood DC, relatively immature DC and mature DC were isolated from hepatic and intestinal lymph, and intravenously transferred to allogeneic hosts. It was then possible to detect small numbers of DC within secondary lymphoid tissues either by immunostaining for donor type major histocompatibility complex class I antigen or, at much higher sensitivity, for bromodeoxyuridine incorporated by proliferating cells (mainly T lymphocytes), which responded to the alloantigen presented by the administered DC. The intravenously injected DC accumulated in the paracortex of regional lymph nodes of the liver via a lymph-borne pathway. Intravenously injected fluorochrome-labeled syngeneic DC behaved similarly. In contrast, very few DC were found in spleen sections and were hardly detectable in other lymph nodes or in other tissues. An in situ cell binding assay revealed a significant and selective binding of DC to Kupffer cells in liver cryosections. It is concluded that rat DC can undergo a blood-lymph translocation via the hepatic sinusoids, but not via the high endothelial venules of lymph nodes. Hence the hepatic sinusoids may act as a biological concentrator of blood DC into the regional hepatic nodes. Kupffer cells may play an important role in this mechanism.
The traffic as well as the significance of dendritic cells
(DC)1 in the blood are not yet completely resolved
(1). When particulates are injected intravenously, particleladen DC appear initially in the blood marginating pool
and then in the peripheral lymph draining the liver (2).
These cells are proven to be relatively immature DC with a
temporary phagocytic activity (2). These and other observations suggest that DC progenitors may be selectively recruited to the liver after intravenous injection of particulates (3), and that they subsequently translocate from the
liver vasculature to the draining hepatic LNs. There have
been few other reports concerning the involvement of the
liver vasculature in the recruitment and translocation of
cells of the DC lineage. After intravenous administration of
radiolabeled mouse splenic DC (4) or of rat lymph DC (5)
to syngeneic hosts, a high radioactivity was found not only
in the spleen but also in the liver. Although the accumulation of DC in the liver was not explained in these reports,
it may imply a specific affinity of DC for the liver vasculature. Fossum (5) noticed subsequent migration of DC to
the celiac nodes, but only mature DC were administered and the significance of this pathway was unclear.
The aim of the present study is to understand the role of
the hepatic sinusoids in the traffic of the rat DC lineage
from the blood. Paramagnetic latex-laden DC in the hepatic lymph were isolated and used as relatively immature
DC (2). Mature DC of either hepatic or intestinal lymph
(6) were also examined. Since a trace number of DC was
difficult to detect in host tissues, the isolated DC were intravenously transferred to allogeneic hosts. DC were then
traced immunohistologically on tissue sections by immunostaining for either donor type MHC class I molecules or for 5-bromo-2 Animals.
Inbred male DA rats (RT1a) were supplied by the
Laboratory Animal Center for Experimental Research (Kumamoto University School of Medicine, Kumamoto, Japan). Lewis
rats (RT11) were purchased from Seac Yoshitomi, Ltd. (Fukuoka,
Japan). Both were reared under specific pathogen-free conditions.
Antibodies.
Mouse mAbs specific for rat determinants, including antibodies against CD2 (OX34), TCR- Isolation of DC.
Collection of DC from either the hepatic or
the intestinal lymph has been described in detail (2, 6). Briefly,
the cells were collected from central thoracic duct lymph of either hepatic or mesenteric lymphadenectomized rats. Immature
DC that had ingested paramagnetic latex (0.8 µm diameter, 0.5 ml/200 g body wt; L0898; Sigma Chemical Co., St. Louis, MO)
in the blood were isolated from the hepatic lymph after intravenous administration of particulates (2). Lymph cells were treated
with mitomycin C before isolation. The purity of latex-laden DC
was 80-90% with the viability of >95%. Contaminated cells were
mainly polymorphonuclear leukocytes. The original unseparated
cells were also used for comparison. Mature DC were also collected from the intestinal lymph and hepatic lymph without intravenous latex injection and were enriched on metrizamide gradients (Nycomed Pharma, Oslo, Norway) (2, 6).
Experimental Design.
Isolated DC from DA rats were intravenously injected into Lewis rats, and at various time intervals after
cell transfer, host proliferating cells were labeled with BrdU and
host tissues were freshly frozen. First, transferred DC were detected by immunostaining donor type MHC class I antigen and by
an existence of latex particles. In a control syngeneic DC transfer
study, DC were labeled with a fluorochrome and chased with a
fluorescence microscope. Second, the host proliferative response
was studied with respect to organ specificity, dose dependence on
donor cells, time kinetics, and phenotype of proliferating cells to
reveal whether they respond to alloantigen presentation by the
transferred DC or not. The number of BrdU-positive (BrdU+)
cell/mm2 of 6-µm thick sections was estimated in a blinded fashion. Control Lewis rats received an intravenous injection of unseparated cell from DA rats or of syngeneic latex-laden DC from
Lewis rats. The germinal center area in the lymph follicle was excluded from assessment since there was a high background proliferative activity of germinal center B cells. Each value was cited as
a mean ± SD of three to six rats, and for some data, statistical
analyses were performed using Student's t test. Third, in situ cell
binding assays were performed to study binding of DC to frozen
sections of various target tissues.
Distribution of Transferred Allogeneic DC.
At 12 h and 1, 2, and
3 d after intravenous transfer of 106 allogeneic latex-laden DC, the
spleen, liver, thymus, Peyer's patches, and the cervical, parathymic, posterior mediastinal, celiac, and mesenteric LNs (9) of hosts
were excised and cryosectioned. Double immunostaining was
performed with RT1Aa (blue), and then with a cocktail of mAbs
to CD2 and TCR- Distribution of Fluorochrome-labeled Syngeneic DC.
DC were labeled with Hoechst dye (H33342; Sigma Chemical Co.), an intracellular DNA-binding fluorochrome, after Brenan et al. (10).
Briefly, mature lymph DC from DA rats were resuspended in
PBS containing 0.1% BSA at a concentration of 3 × 105/ml, 12 µg/ml of H33342 was added, and the cells were incubated for 15 min in a 37°C water bath. Labeling was stopped by adding cold
medium and cells were washed. 106 of DC were intravenously
transferred into DA rats, and host tissues were removed 1 d after
transfer. Cryosections of the tissues were examined for presence
of fluorescent cells under a fluorescence microscope at a wavelength exciting H33342 (365 nm).
Analysis of Proliferative Response to Transferred Allogeneic DC.
In
all cell transfer studies, host rats received an intravenous injection of
BrdU (2 mg/0.5 ml saline/100 g body weight; Sigma Chemical
Co.) 1 h before killing. 106 of allogeneic latex-laden DC, allogeneic unseparated cells, or syngeneic latex-laden DC were intravenously transferred to hosts. Host rats were killed 3 d after cell
transfer, and cryosections of the tissues were immunostained with
an anti-BrdU mAb (11). For the dose-response study, different
numbers of allogeneic cells, 104-106 for latex-laden DC, or 105-
108 for unseparated cells, were intravenously transferred to hosts. The celiac LNs were examined 3 d after cell transfer. For the time
kinetics study, 3 × 105 of allogeneic latex-laden DC were intravenously injected into hosts. Immediately (0 d), 1, 2, 3, 4, 5, and 7 d
after cell transfer, the celiac LNs were examined. To examine cell
phenotypes, mAb cocktails to CD2 and TCR- In Situ Cell Binding Assay.
Binding of DC to frozen sections
was studied with a slight modification of previous reports (7, 8).
Briefly, unfixed cryosections (6 µm) of liver and other tissues of
either Lewis or DA rats were air dried for 1-4 h. Either latexladen DC, mature DC, or unseparated cells from lymph of DA rats
were resuspended in RPMI 1640 containing 5% FCS and 5 mM
Hepes at a concentration of 106/ml. Cryosections were overlaid
with 50 µl of cell suspension/section and incubated horizontally at
37°C in a humidified incubator for 30 min. Cell suspensions were
then carefully aspirated, washed gently, and samples were fixed in
formol calcium solution (2) for 3 min and fixed further with 1%
glutaraldehyde in PBS for 1 min. Some sections were directly examined under a differential interference light microscopy. Other
sections were double immunostained with RT1Aa (blue-black)
and ED2 (brown) to detect allogeneic DC and Kupffer cells (2),
respectively, as described (6).
On cytosmears, >95%
of isolated paramagnetic latex-laden DC of DA rats were
RT1Aa+ with clearly recognizable latex particles in their
cytoplasm (Fig. 1). 1 d after intravenous transfer of 106 latex-laden DC to allogeneic hosts, RT1Aa+ cells located
mainly in the paracortex of both celiac (Fig. 2) and parathymic LNs, the number being 66.7 ± 30.4 and 17.4 ± 9.9 cells/section, respectively. Both celiac and parathymic
LNs are regional LNs of the liver (2, 9). At an early stage
after cell transfer (12 h), donor DC were already found in
the marginal sinus and interfollicular area of the celiac LNs.
The numbers of donor DC quickly declined by 2 d and almost disappeared by 3 d. Comparable numbers of mature
allogeneic DC of either hepatic and intestinal lymph were
also found in the regional hepatic LNs (not shown). In
contrast, very few DC were found in the spleen (approximately one cell/section), and they were hardly detectable in other LNs or in other tissues. Syngeneic fluorochrome-
labeled DC were easily detected by their blue fluorescent
nuclei under a fluorescence microscope. They accumulated
mainly in the hepatic LNs (35.5 ± 18.1 cells/section of the
celiac LNs) in a similar manner as allogeneic DC.
After
transfer of 106 allogeneic latex-laden DC, a significant increase
in host cell proliferation as detected by BrdU-labeling was
observed in the celiac LNs, parathymic LNs, and periarterial lymphoid sheath of the spleen, but not in other LNs or
other tissues (P <0.05 when compared with 106 syngeneic
latex-laden DC) (Figs. 3 and 4). An insignificant but relatively higher proliferative response was seen in the posterior mediastinal LNs, which may be due to the presence of
lymphatic communications of these LNs with ascending
lymphatics of the liver (2). BrdU+ cells were mostly observed in the paracortex of the LNs (Fig. 5) and within the
periarterial lymphoid sheath and the terminal arteriolar region in the red pulp of the spleen. The terminal arteriolar
region is a protrusion of the periarterial lymphoid sheath
and functionally equivalent to the latter (11). Allogeneic mature DC also induced proliferative response similar to allogeneic latex-laden DC (not shown). Allogeneic unseparated cells did not induce a significant proliferative response
in most tissues; however, the spleen showed a proliferative
response slightly weaker but comparable to that after transfer of allogeneic DC (Fig. 4). The dose-response study of
the celiac LNs (Fig. 6) revealed that as few as 105 allogeneic
DC induced significant proliferation, and that the maximum response at 3 d was achieved by transfer of 3 × 105
and 106 allogeneic DC. On the other hand, allogeneic unseparated cells showed much weaker stimulation in that
100 times more unseparated cells were required to induce a
similar level of proliferative response as for DC. The time
kinetic study of the celiac LNs (Fig. 7) showed a slight increase of BrdU+ cells at 1 d and a significant proliferation
2-3 d after 3 × 105 allogeneic transfer. The ratio of BrdU+
T cells, BrdU+ B cells, and BrdU+ macrophages was 85:14:1
in the superficial cortex, 91:4:7 in the paracortex, and 82:
11:7 in the medulla. This indicates that proliferating cells
were mainly of the T cell lineage (Fig. 8).
Isolated lymph DC showed
preferential binding to either allogeneic or syngeneic liver
cryosections (Fig. 9) compared with other tissues such as
spleen, lung, thymus, and LN. The number of bound DC/
mm2 section in the liver was approximately two to three
times more than those in the other tissues. The same concentration of unseparated cells showed less binding to the
liver cryosections than DC (Fig. 9 b). The ratio of RT1Aa+
cells associated or not with ED2+ cells was 2.3-4.0, indicating a significant and selective binding of DC to Kupffer
cells in the sections (Fig. 10).
In this study, T cell proliferation was selectively induced
in the thymus-dependent area of the regional hepatic LNs after intravenous transfer of allogeneic immature latex-laden
DC, but not of allogeneic unseparated cells or syngeneic latex-laden DC. This probably represents a specific immune
response against alloantigen presented by transferred DC.
Together with the RT1Aa immunostaining study, the results demonstrate a preferential accumulation of allogeneic
immature DC in the paracortex of the regional hepatic
LNs. Since mature allogeneic DC and syngeneic DC also
showed a similar accumulation pattern, this traffic is common
among all types of transferred DC examined and not affected by MHC barriers, as for DC traffic to the mouse
spleen (4). The absence of transferred DC in LNs other
than the regional hepatic LNs and the initial appearance of
DC in the marginal sinus of the regional hepatic LNs at an
early stage after cell transfer suggest that the cells enter the
LN via the afferent lymph after undergoing blood-lymph
translocation in the liver. These and other (4) results, as
well as the insignificant binding of DC to LN sections, also
indicate that direct entry of DC via the high endothelial
venules is unlikely. In this respect, DC are considered to
lack some cell membrane constituent or receptor that
would allow them to interact with the high endothelial
venules (4).
This unique migratory pattern of DC in the blood also
supports the speculation in the previous study (2) that the
particle-laden DC in the hepatic lymph represent cells that
have been recruited to the liver and undergone the blood-
lymph translocation after phagocytosing the intravenously
administered particles. The cells may be recruited as DC
progenitors, possibly in response to the intravenous particulates (3), and then develop into a phagocytic stage before
the translocation event.
The initial appearance of latex-laden DC in the sinusoidal area, but not in the portal or hepatic vein area, after intravenous injection of latex particles (2) implies that the site
for the blood-lymph translocation is the sinusoid. Localization of labeled mouse DC in the hepatic sinusoids after intravenous transfer has also been described (4). In mitogenstimulated mouse liver, accumulation of lymphocytes in the
space of Disse and then in the Glisson's sheath is observed
(12). Hence, it is suggested that DC attach to the vessel
wall in the sinusoidal area, pass through the space of Disse
to the connective tissue stroma of either the portal or hepatic vein area, and then enter the initial lymphatic ducts
located there. Taken together, the present study demonstrates that both mature and immature rat DC in the blood preferentially undergo hepatic sinusoids-lymph translocation in an MHC-independent fashion and accumulate in
the regional hepatic LNs, and further suggests that autologous blood DC may behave similarly to the transferred DC
studied here.
The mechanisms and the factors that regulate this translocation are unknown. Selective translocation may imply
that sinusoidal lining cells express certain adhesion molecules by which DC can attach the sinusoidal wall before
initiating translocation. The in situ cell binding assay suggests that Kupffer cells in the hepatic sinusoids are capable
of selectively trapping DC from the blood. Frequent observations of the close association of DC with Kupffer cells in
the liver section in normal steady state and after latex injection (2) also support this idea. The cell transfer and cell
binding assays have revealed that this translocation event
can occur even in a donor-host combination of normal
steady state, suggesting that de novo elaboration of migratory stimuli such as cytokines (13) may not be necessary.
On the other hand, Kupffer cell activation might be essential for the recruitment of DC progenitors to the liver,
since hepatic lymph under the steady state contain mostly
mature DC (6) and the recruitment was induced by intravenous injection of particulate matters (2). In this respect,
the accumulation of CFU-spleen in the mouse liver after
estrogen treatment is considered to be due to trapping of CFU-spleen by Kupffer cells that have been activated by
estrogen, a potent activator of the mouse macrophage lineage (14). Lymphocytes also translocate from the sinusoid
to hepatic lymph (15), possibly by similar mechanisms, although an involvement of Kupffer cells is not certain.
The significant proliferative response was induced even
when only a trace number of allogeneic DC was detectable
in lymphoid tissues, e.g., in the spleen, where approximately one cell/section was found. In addition, a minimum
number (105) of intravenous allogeneic DC could induce a
significant proliferative response in the regional hepatic LNs
of the host. Usually 105 transferred cells are difficult to trace
in vivo because they are diluted after entering the systemic
circulation. Therefore, the result demonstrates that the proliferation assay is a very sensitive technique for detecting
not only the presence of an immune response, but also the
presence of a trace number of antigen presenting cells, and
that blood DC are very effectively concentrated in the regional hepatic LNs. In other words, the hepatic sinusoids may act as a biological concentrator of DC into regional
LNs. In contrast, the proliferative response in the spleen to
allogeneic unseparated cells, which was comparable to that
of DC, may be due to preferential accumulation of recirculating lymphocytes in the white pulp (4, 5). Together, the
result indicates more efficient accumulation of DC in the
hepatic LNs than in the spleen, especially when small number were transferred.
The reason for the presence of only few DC in spleen
sections in this study compared with the considerable accumulation of radiolabeled DC in other reports (4, 5) is unclear. Since the spleen is much bigger than the hepatic
LNs, DC may be more dispersed in the splenic tissues than
in the hepatic LN, and therefore, it might be more difficult
to find DC in the spleen sections even if total number of
DC within the spleen is high. In a preliminary study of rat
liver allotransplantation, a significant number of donor DC
were observed in the periarterial lymphoid sheath of the
host spleen within a few days after transplantation (Matsuno, K., S. Kudo, N. Miyanari, T. Ezaki, and M. Ogawa, unpublished data). This suggests that resident DC in the liver also
migrate to the spleen via the blood if the liver is transplanted to allogeneic hosts as in transplantation of other organs (1), although we can not examine the hepatic LNs
since lymphatic connections are interrupted by surgery. Alternatively, some difference in trafficking of DC to either
the spleen or the hepatic LNs may exist among different types
of DC. Accumulating evidence concerning heterogeneities of
DC (13) may support this possibility. Migration pattern of different types of DC is currently under study.
Fossum (5) found that the labeled DC proceeded from
the liver to the celiac LNs via afferent lymphatics, but the
significance of this DC translocation was not clear. The
present study demonstrates this traffic as a novel and definite
migration pathway for rat DC from the blood. The regional hepatic LNs might become an important site for immunoproliferation in response to blood-borne antigen, including gut-derived antigen carried by DC via the portal
vein, or to allograft-derived DC as the extrinsic sensitization outside of graft (1). The transfer study would also be
useful as a simulation model for studying blood-borne migration kinetics of donor DC from transplants.
-deoxyuridine (BrdU) incorporated by proliferating cells that had responded to the alloantigen presented by the donor DC. An in situ cell binding assay (7, 8)
was also performed to examine the capacity of DC to bind
to the liver vasculature; the samples were further immunostained with some cell markers to reveal whether or not
DC bind to a specific cell type.
(R73), macrophage-related antigens (ED1, ED2, and ED3), and a polymorphic
MHC class I of DA rat (anti-RT1Aa, MN9-41-6), were obtained
from Sera-Lab Ltd. (Crawley Down, Sussex, UK). mAbs to a
pan-B cell marker (reference 2; HIS14; provided by Dr. F.G.M.
Kroese, University of Groningen, Groningen, The Netherlands)
and IgM (MARM-4; provided by Dr. H. Basin, Louvain University, Brussels, Belgium) were donated. An mAb against BrdU was
purchased from Novocastra Laboratories Ltd. (Newcastle upon Tyne, UK).
(brown) as described (6). In the case of latex-laden DC, the donor origin of RT1Aa+ cells was confirmed
by the presence of latex particles within the cells.
for T cells; pan
B and IgM for B cells; or ED1, ED2, and ED3 for macrophages
were used. The celiac LNs were removed 3 d after intravenous
transfer of 106 allogeneic latex-laden DC, and double immunostaining of cell marker (blue) and BrdU (red) was performed as
described (11). The number of double-positive cells was counted
with respect to the three structural domains of the celiac LNs,
namely, the superficial cortex, paracortex, and medulla, and the
ratio of BrdU+ T cells, BrdU+ B cells, and BrdU+ macrophages
in each domain was estimated.
Distribution of Transferred DC.
Fig. 1.
RT1Aa immunostaining of cytosmears of paramagnetic latex-laden DC from hepatic lymph of a DA rat. More than 95% of isolated latexladen DC were RT1Aa+ (blue) with clearly recognizable particles in their cytoplasm. ×1,300.
Fig. 2.
Accumulation of latex-laden DC in the celiac LN 1 d after cell transfer. Double immunostaining of RT1Aa (blue) and CD2 and TCR-
(brown). (a) Under low magnification, RT1Aa cells are localized in the paracortex (PC), which are populated with host T cells (brown). F, lymph follicle in
the superficial cortex. (b) At higher magnification of the paracortex, four RT1Aa+ cells with dendritic cytoplasmic processes are clustering with host T
cells (brown). Most of them contain recognizable particles in their cytoplasm (arrows). (a), ×115; (b), ×730.
Fig. 5.
Proliferative response in the celiac LN 3 d after cell transfer detected by BrdU labeling. Compared to normal state, (a) 105 unseparated cells
did not induce a significant increase in the number of BrdU+ cells (red), but (b) 105 latex-laden DC induced a significant proliferation (see also Fig. 3) in
the paracortex (PC). G, germinal center in the superficial cortex. ×115.
Fig. 8.
Phenotype of proliferating cells 3 d after transfer of 3 × 105 allogeneic DC. Paracortex near the medulla of the celiac LNs. Double immunostaining of CD2 and TCR- (blue) and BrdU (red). Note proliferating cells were mainly T cell lineage (double positive cells). ×520.
Fig. 10.
In situ cell binding assay followed by double immunostaining with RT1Aa (blue black) and ED2 (brown). (a) Under lower magnification, DC
(RT1Aa+) show a distribution pattern similar to that of Kupffer cells (ED2+) in the liver lobules. (b) At higher magnification of the liver lobule examined
under a differential interference microscope, associations of bound DC with Kupffer cells are frequently observed (arrows). Ratio of RT1Aa+ cells associated with ED2+ cells to those without the association was 2.3-4.0. (a), ×64; (b), ×250.
[View Larger Version of this Image (127K GIF file)]
Fig. 3.
Proliferative response in host tissues 3 d after 106 cell transfer.
After transferring allogeneic latex-laden DC, the celiac and parathymic
LNs showed a significant increase in the number of BrdU+ cells (*P = 0.03) compared with that after transfer of unseparated cells and syngeneic
latex-laden DC. In posterior mediastinal LNs, there was no significant
difference in proliferation between allogeneic and syngeneic latex-laden
DC. No significant proliferative response was observed in cervical or mesenteric LNs, or (data not shown) Peyer's patches, liver, and thymus. Data
are expressed as mean ± SD. Bars represent SD. Three rats per group
were examined.
[View Larger Version of this Image (35K GIF file)]
Fig. 4.
Proliferative response in host spleen 3 d after 106 cell transfer.
Allogeneic latex-laden DC and unseparated cells induced host cell proliferation, but there was no significant difference between them (P >0.05).
Data are expressed as mean ± SD. Bars represent SD. Three rats per
group were examined.
[View Larger Version of this Image (37K GIF file)]
Fig. 6.
The dose responsiveness of the proliferative response in celiac LNs 3 d after cell transfer. Allogeneic latex-laden DC induced a significant increase at a dose of 105 (P = 0.03 when compared with unseparated cells) and the maximum response at a dose of 3 × 105 and 106 cells.
In contrast, 100 times more allogeneic unseparated cells were required to
induce a comparable proliferative response. Data are expressed as mean ± SD. Bars represent SD. Three to six rats per group were examined.
[View Larger Version of this Image (18K GIF file)]
Fig. 7.
The time kinetics of the proliferative response in celiac LNs
after transfer of 3 × 105 allogeneic DC. A slight increase of BrdU+ cells at
1 d, but significant proliferation 2-3 d, after cell transfer were observed.
Data are expressed as mean ± SD. Bars represent SD. Three to six rats per
group were examined.
[View Larger Version of this Image (47K GIF file)]
Fig. 9.
In situ cell binding assay examined under differential interference light microscopy. DC showed preferential binding to either allogeneic (a)
or syngeneic (not shown) liver cryosections compared to other tissues. In spleen (c), DC attached mainly to the marginal zone (Z) but not to the white
pulp (W). In LN (d), bound DC were not obviously localized to specific areas. The same concentration of unseparated cells showed less binding to the
liver cryosections than DC (b). P, portal area; M, medulla; C, cortex. ×160.
[View Larger Version of this Image (116K GIF file)]
Address correspondence to Dr. Kenjiro Matsuno, Department of Anatomy II, Kumamoto University School of Medicine, 2-2-1, Honjo, Kumamoto 860, Japan.
Received for publication 16 September 1996
1Abbreviations used in this paper: BrdU, 5-bromo-2We are grateful to Dr. Jonathan M. Austyn for critically reviewing the manuscript and for helpful discussions. Professors Yasuo Uehara, Hideo Hayashi, and Masahiko Kotani are also acknowledged for their valuable suggestions and encouragement.
This work was supported by a Grant-in-Aid for Scientific Research (C) No. 08670022 (partly) from the Japanese Ministry of Education, Science, and Culture.
1. | Austyn, J.M., and C.P. Larsen. 1990. Migration patterns of dendritic leukocytes: implications for transplantation. Transplantation (Baltimore) 49: 1-7 [Medline] . |
2. | Matsuno, K., T. Ezaki, S. Kudo, and Y. Uehara. 1996. A life stage of particle-laden rat dendritic cells in vivo: their terminal division, active phagocytosis, and translocation from the liver to the draining lymph. J. Exp. Med 183: 1865-1878 [Abstract] . |
3. | Austyn, J.M.. 1996. New insights into the mobilization and phagocytic activity of dendritic cells. J. Exp. Med 183: 1287-1292 [Medline] . |
4. | Kupiec-Weglinski, J.W., J.M. Austyn, and P.J. Morris. 1988. Migration patterns of dendritic cells in the mouse: traffic from the blood, and T cell-dependent and -independent entry to lymphoid tissues. J. Exp. Med 167: 632-645 [Abstract] . |
5. | Fossum, S.. 1988. Lymph-borne dendritic leukocytes do not recirculate, but enter the lymph node paracortex to become interdigitating cells. Scand. J. Immunol. 27: 97-105 [Medline] . |
6. | Matsuno, K., S. Kudo, T. Ezaki, and K. Miyakawa. 1995. Isolation of dendritic cells in the rat liver lymph. Transplantation (Baltimore). 60: 765-768 [Medline] . |
7. | Austyn, J.M., J.W. Kupiec-Weglinski, D.F. Hankins, and P.J. Morris. 1988. Migration patterns of dendritic cells in the mouse: homing to T cell-dependent areas of spleen, and binding within marginal zone. J. Exp. Med. 167: 646-651 [Abstract] . |
8. | Van den Berg, T.K., J.J.P. Brevé, J.G.M.C. Damoiseaux, E.A. Döpp, S. Kelm, P.R. Crocker, C.D. Dijkstra, and G. Kraal. 1992. Sialoadhesin on macrophages: its identification as a lymphocyte adhesion molecule. J. Exp. Med. 176: 647-655 [Abstract] . |
9. | Tilney, N.L.. 1971. Patterns of lymphatic drainage in the adult laboratory rat. J. Anat. 109: 369-383 [Medline] . |
10. | Brenan, M., C.R. Parish, and G.I. Schoefl. 1985. Topographical studies of lymphocyte localization using an intracellular fluorochrome. Anat. Rec. 213: 421-428 [Medline] . |
11. | Matsuno, K., T. Ezaki, and M. Kotani. 1989. Splenic outer periarterial lymphoid sheath (PALS): an immunoproliferative microenvironment constituted by antigen-laden marginal metallophils and ED2-positive macrophages in the rat. Cell Tissue Res. 257: 459-470 [Medline] . |
12. | Fujikura, S., H. Mizuhara, Y. Miyazawa, H. Fujiwara, and K. Kaneda. 1996. Kinetics and localization of lymphoblasts that proliferate in the murine liver after Concanavalin A administration. Biomed. Res. 17: 129-139 . |
13. | Caux, C., Y.-J. Liu, and J. Banchereau. 1995. Recent advances in the study of dendritic cells and follicular dendritic cells. Immunol. Today. 16: 2-4 [Medline] . |
14. | Hayama, T., Y. Nawa, T. Ezaki, and M. Kotani. 1983. Effects of estrogen on hepatic hemopoiesis in the adult mouse. Exp. Hematol. (NY) 11: 611-617 . |
15. | Smith, M.E., A.F. Martin, and W.L. Ford. 1980. Migration of lymphoblasts in the rat: preferential localization of DNAsynthesizing lymphocytes in particular lymph nodes and other sites. Monogr. Allergy. 16: 203-232 [Medline] . |