The entry of T and B lymphocytes into rat popliteal lymph nodes undergoing a graft-versus-host reaction

The entry of radiolabeled blood-borne T and B lymphocytes into resting popliteal lymph nodes and popliteal lymph nodes stimulated with semiallogeneic lymphocytes was investigated in rats. Thoracic duct lymphocytes separated into T- and B-lymphocyte populations on nylon-wool columns were radiolabeled with 51chromium and equal numbers of T or B lymphocytes were injected intravenously. While the ratio of T and B lymphocytes in the blood is approximately 3:1 it was found that the ratio of T to B lymphocytes migrating into lymph nodes was approximately 9 T to 1 B lymphocyte in both resting and antigenically stimulated lymph nodes. Since the ratio of T to B lymphocytes in thoracic duct lymph is similar to that of blood, there is a disparity between the number of T cells entering and leaving lymph nodes. These results suggest that some T lymphocytes may return to the blood directly and/or there is increased T lymphocyte death in lymph nodes.     

Cytokine- and Ig-producing T cells in mucosal effector tissues: analysis of IL-5- and IFN-gamma-producing T cells, T cell receptor expression, and IgA plasma cells from mouse salivary gland-associated tissues.

The present study has focused on the analysis of cytokine- and Ig-producing mononuclear cells (MC) that reside in the salivary glands and their associated tissues (SGAT) in the oral region. The SGAT are located under the mandibular area and consist of submandibular glands, periglandular lymph nodes, and cervical lymph nodes. MC were isolated from individual SGAT and examined for T cell subsets and TCR expression, in comparison with T cells obtained from other mucosa-associated and systemic tissues. Forty to fifty percent of MC in submandibular glands were CD3+ T cells, equally divided into CD4+ CD8- and CD4- CD8+ T cell subsets. On the other hand, the intestinal lamina propria and Peyer's patches possessed a approximately 2 to 3:1 ratio of CD4+ CD8- to CD4- T cells. A high frequency of CD4- CD8- (double negative) (DN) T cells (approximately 6 to 10%) was also isolated from submandibular glands. In contrast, approximately 70 to 90% of MC in periglandular lymph nodes and cervical lymph nodes were CD3+ T cells and like the peripheral lymph nodes consisted of fivefold higher numbers of CD4+ CD8- than CD4- CD8+ T cells, with low numbers of DN cells (less than 5%). When expression of gamma/delta and alpha/beta TCR was examined in individual T cell subsets of submandibular glands, the CD4- CD8+ and DN T cell fractions contained 25% and 100% gamma/delta TCR+ cells, respectively. On the other hand, essentially all CD4+ CD8- T cells in SGAT as well as CD4- CD8+ cells in periglandular lymph nodes and cervical lymph nodes were alpha/beta TCR+ T cells. When cytokine production was examined by using IFN-gamma- and IL-5-specific enzyme-linked immunospot assays, the CD3+ CD4+ CD8- T cells in submandibular glands contained T cells spontaneously producing IFN-gamma and IL-5. Further, IL-5 spot-forming cells (SFC) were two- to threefold greater in number, compared with IFN-gamma SFC. The periglandular lymph node T cells contained cytokine producing cells with a ratio of 2:1 for IL-5 and IFN-gamma SFC cells, whereas cervical lymph node T cells did not produce cytokines unless stimulated with T cell mitogens. When the isotype distribution of Ig-producing cells was examined among SGAT, submandibular glands contained large numbers of IgA-producing cells, with few IgM- and IgG-producing cells, a pattern similar to that of the lamina propria. Further, elevated numbers of IgA-secreting cells were also seen in periglandular lymph nodes but not in cervical lymph nodes.(ABSTRACT TRUNCATED AT 400 WORDS)     

The role of dendritic cells in the initiation of immune responses to contact sensitizers. I. In vivo exposure to antigen

Twenty-four hours after skin painting mice with picryl chloride (PIC) there was a four- to fivefold increase in the numbers of dendritic cells (DC) isolated from the lymph nodes. These DC initiated primary proliferative and cytotoxic responses when added to cultures of normal syngeneic lymph node cells. The proliferative response was enhanced when the donors of the responding lymph node cells were sensitized with the same antigen. Contact sensitivity developed in syngeneic mice injected into the footpads with 30,000-50,000 DC from lymph nodes of mice painted with picryl chloride 1 day previously. Thus, 1 day after skin painting mice, there were dendritic cells in the draining lymph nodes which were able both to initiate primary stimulation of lymphocytes in vitro and to sensitize recipient mice to give specific delayed hypersensitivity reactions.     

Chronic alcohol consumption decreases the percentage and number of NK cells in the peripheral lymph nodes and exacerbates B16BL6 melanoma metastasis into the draining lymph nodes

NK cells in the lymph nodes play important roles in inhibiting tumor metastasis into draining lymph nodes. Previously, we reported that chronic alcohol consumption interferes with NK cell trafficking from the bone marrow to the spleen. Herein, we found that alcohol consumption decreases the numbers of NK cells in lymph nodes. Adoptive transfer experiments indicated that continued exposure of donor splenocytes to alcohol inhibits NK but not T cell trafficking to lymph nodes. Alcohol did not negatively affect CCR7⁺ and CXCR3⁺ NK cells, but decreased the percentage and number of CD62L⁺ NK cells in the spleen, which are an important source of NK cell trafficking into the lymph nodes. These data suggest that modulation of the microenvironment associated with alcohol consumption impairs the trafficking of NK cells to lymph nodes. The decreased number of NK cells in the lymph nodes was associated with increased melanoma metastasis into the draining lymph nodes.     

Lymphocyte traffic through lymph nodes and Peyer's patches of the rat: B- and T-cell-specific migration patterns within the tissue,and their dependence on splenic tissue

The migration routes of lymphocyte subsets through organ compartments are of importance when trying to understand the local events taking place during immune responses. We have therefore studied the traffic of B, T, CD4⁺, and CD8⁺ lymphocytes through lymph nodes and Peyer's patches. At various time points after injection into the rat, labeled lymphocytes were localized, and their phenotype characterized in cryostat sections using immunohistochemistry. Morphometry was also performed, and the recovery of ⁵¹Cr-labeled lymphocytes in these organs was determined. B and T lymphocytes entered the lymph nodes via the high endothelial venules in similar numbers. Most B lymphocytes migrated via the paracortex (T cell area) into the cortex (B cell area), and then back in substantial numbers into the paracortex. In contrast, T lymphocytes predominantly migrated into the paracortex and were rarely seen in the cortex. No obvious differences were seen between various lymph nodes and Peyer's patches and the routes of CD4⁺ and CD8⁺ lymphocytes. After injection of lymphocytes into animals with autotransplanted splenic tissue, the number of B lymphocytes that had migrated into the B cell area of lymph nodes and of Peyer's patches was significantly decreased, whereas CD4⁺ lymphocytes migrated in larger numbers into the T cell area of both organs.This study was supported by the Deutsche Forschungsgemein-schaft (SFB 244, A7).     

Experimental Trypanosoma cruzi infection alters the shaping of the central and peripheral T-cell repertoire

We investigated the thymic and peripheral T-lymphocyte subsets in BALB/c mice undergoing acute or chronic Trypanosoma cruzi infection, in terms of expression of particular Vbeta rearrangements of the T-cell receptor. We first confirmed the severe depletion of CD4(+)CD8(+) thymocytes following acute T. cruzi infection. By contrast, the numbers of CD4(+)CD8(+) cells in subcutaneous lymph nodes increased up to 16 times. In subcutaneous lymph nodes, we found CD4(+)CD8(+) cells that expressed prohibited segments TCRVbeta5 and TCRVbeta12 (which are physiologically deleted in the thymus of BALB/c mice), as did some mature single-positive cells (CD4(+)CD8(-) and CD4(-)CD8(+)). In the thymus of infected animals, although higher numbers of immature cells bearing such Vbeta segments were seen, they were no longer detected in the mature single-positive stage, suggesting that negative selection occurs normally. We also found increased numbers of cells bearing the potentially autoreactive phenotype TCRVbeta5(+) and TCRVbeta12(+) in T-lymphocyte subsets from subcutaneous lymph nodes of T. cruzi chronically infected mice. In conclusion, our data indicate that immature T lymphocytes bearing prohibited TCRVbeta segments leave the thymus and gain the lymph nodes, where they further differentiate into mature CD4(+) or CD8(+) cells. Conjointly, these findings show changes in the shaping of the central and peripheral T-cell repertoire in both acute and chronic phases of murine T. cruzi infection. The release of potentially autoreactive T cells in the periphery of the immune system may contribute to the autoimmune process found in both murine and human Chagas' disease.     

Persistent Autoantibody-Production by Intermediates between Short-and Long-Lived Plasma Cells in Inflamed Lymph Nodes of Experimental Epidermolysis Bullosa Acquisita

Autoantibodies are believed to be maintained by either the continuous generation of short-lived plasma cells in secondary lymphoid tissues or by long-lived plasma cells localized in bone marrow and spleen. Here, we show in a mouse model for the autoimmune blistering skin disease epidermolysis bullosa acquisita (EBA) that chronic autoantibody production can also be maintained in inflamed lymph nodes, by plasma cells exhibiting intermediate lifetimes. After EBA induction by immunization with a mCOL7c-GST-fusion protein, antigen-specific plasma cells and CD4 T cells were analyzed. Plasma cells were maintained for months in stable numbers in the draining lymph nodes, but not in spleen and bone marrow. In contrast, localization of mCOL7c-GST -specific CD4 T cells was not restricted to lymph nodes, indicating that availability of T cell help does not limit plasma cell localization to this site. BrdU-incorporation studies indicated that pathogenic mCOL7c- and non-pathogenic GST-specific plasma cells resemble intermediates between short-and long-lived plasma cells with half-lives of about 7 weeks. Immunization with mCOL7c-GST also yielded considerable numbers of plasma cells neither specific for mCOL7c- nor GST. These bystander-activated plasma cells exhibited much shorter half-lives and higher population turnover, suggesting that plasma cell lifetimes were only partly determined by the lymph node environment but also by the mode of activation. These results indicate that inflamed lymph nodes can harbor pathogenic plasma cells exhibiting distinct properties and hence may resemble a so far neglected site for chronic autoantibody production.     

Visceral fat accumulation induced by a high-fat diet causes the atrophy of mesenteric lymph nodes in obese mice

Objective: A high intake of fat in the diet plays a crucial role in promoting obesity and obesity‐related pathologies, and especially visceral obesity is closely associated with obesity‐related complications. Because adipose tissue is anatomically associated with lymph nodes, the secondary lymphoid organ, we hypothesized that fat tissue‐derived factors may influence the cellularity of lymphoid tissue embedded in fat. Methods and Procedures: Mesenteric and inguinal lymph nodes were isolated from obese mice fed a high‐fat diet and control mice fed a regular diet. T‐cell population, activation state, and the extent of apoptosis were determined by flow cytometric analysis or terminal deoxynucleotidyl transferase biotin‐dUTP nick end labeling (TUNEL) assay. Results: The weight of mesenteric lymph nodes and the total number of lymphoid cells in the obese mice significantly decreased compared with those in the control mice; however, no change was observed in the weight of inguinal lymph nodes. The numbers of CD4⁺ and CD8⁺ T cells in the mesenteric lymph nodes of obese mice significantly decreased compared with those of the control. Enhanced T‐cell activation and apoptosis were observed in the mesenteric lymph node cells of the obese mice. The treatment of lymph node cells with free fatty acids, oxidative stress, and chylomicrons, which are obesity‐related factors, resulted in lymph node T‐cell activation and apoptosis. Discussion: These results suggest that visceral fat accumulation with a high‐fat diet can cause the atrophy of mesenteric lymph nodes by enhancing activation‐induced lymphoid cell apoptosis. Dietary fat‐induced visceral obesity may be crucial for obesity‐related immune dysfunction.     

Further evidence for the existence of B-lymphocyte subpopulations.

We have studied the homing properties of B lymphocytes by using ⁵¹Cr-labeled lymphoid cells obtained from athymic, nu/nu mice, and animals made T-lymphocyte deficient by thymectomy and lethal irradiation followed by reconstitution with syngeneic bone marrow. Comparison was made to the patterns of distribution observed when cell preparations containing normal numbers of T and B lymphocytes were migrated. A small but significant percentage of labeled lymphocytes from lymph nodes, spleen, Peyer's Patches, and bone marrow of T-cell-deficient animals was shown to be lymph node seeking. Secondary transfers of lymph node cells from primary recipients caused enrichment of this lymph node-seeking population. Treatment of T-lymphocyte-deficient lymphoid cell preparations with neuraminidase reduced the percentages of cells homing to the lymph nodes. The data showed that B lymphocytes exhibit unique homing properties when injected into normal recipients. In addition, direct comparison of the homing patterns of B lymphocytes prepared from spleen and lymph nodes of athymic mice revealed differences suggesting that these lymphoid organs contained unique mixtures of at least two different kinds of B cell. The evidence supports the notion that the B-lymphocyte populations contain at least two subpopulations, one of which possesses the ability to home to lymph nodes.     

Immunosuppression in a murine B cell leukemia (BCL1): role of an adherent cell in the suppression of primary in vitro antibody responses

The ability of lymph node cells from mice bearing the BCL1 tumor to respond in vitro to mitogens, allogeneic cells, and both TI and TD antigens was investigated. The lymph nodes of such mice are not invaded with tumor cells and contain normal numbers of T and B cells. Nevertheless, at the peak of tumor burden in the spleen and blood (approximately 8 to 12 wk after injection with tumor cells), the lymph node cells from the tumor-bearing mice display markedly decreased responsiveness both to allogeneic cells and to antigens. In addition, small numbers of lymph node cells from the tumor-bearing mice suppress primary antibody responses of normal lymph node cells. This nonspecific suppression of antibody responses is mediated by a G-10 Sephadex adherent, non-T, non-B cell present in the nodes of the tumor-bearing mice. Since the BCL1 tumor model is in many respects similar to the prolymphocytic type of human chronic lymphocytic leukemia, the present results may be helpful in elucidating the mechanisms underlying the in vivo immunosuppression associated with lymphocytic neoplasms in humans.     

Cytotoxic lymphocytes in B-cell chronic lymphocytic leukemia. A flow cytometric study of peripheral blood, lymph nodes and bone marrow.

The occurrence of cytotoxic lymphocyte subpopulations (i.e., CD 16+, CD 57+ and cytotoxic CD 8+) wa studied in the peripheral blood of 18 B-cell chronic lymphocytic leukemia (B-CLL) patients. The absolute numbers of CD 57+, CD 16+ and cytotoxic CD 8+ lymphocytes were increased in the peripheral blood of untreated patients as compared with healthy donors, suggesting a causal relation with the accumulation of malignant B-cells. For 5 B-CLL patients and 5 hematological normal donors, the lymphocyte subpopulations in peripheral blood, lymph nodes and bone marrow were determined. A significant immune response was observed in the lymph nodes of the patients, as reflected by the CD 3+ lymphocytes, which were 1.7-27 times larger in the patients lymph nodes than in their peripheral blood and bone marrow. In contrast, with peripheral blood this was mainly caused by an increase in CD 4+ lymphocytes. The CD 57 lymphocytes in the lymph nodes of the patients had abnormal orthogonal light-scattering signals and an abnormal density of CD 57+ receptors in comparison with their peripheral blood CD 57+ lymphocytes or the CD 57+ lymphocytes in the peripheral blood, bone marrow and tonsils of the hematological normal donors. This study shows that although a significant increase of cytotoxic lymphocytes in the peripheral blood of B-CLL patients is observed, the actual distributions of the non-malignant lymphocytes can be quite different at the actual tumor sites, i.e., bone marrow and lymph nodes.     

Experimental Brucella abortus infection in wolves

Four juvenile male wolves (Canis lupus) each received an oral dose of 1.6-1.7 x 10(12) colony-forming units of Brucella abortus biovar 1 isolated from a bison (Bison bison) in Wood Buffalo National Park (Canada), and two others served as negative controls. Infected wolves did not show clinical signs of disease but did develop high Brucella antibody titers. Small numbers of B. abortus were excreted sporadically in feces until day 50 postinoculation (PI). Very small numbers of the bacterium were isolated from urine of only one wolf late on the same day that it was infected, and very small numbers of colonies of B. abortus were obtained from buccal swabs of three wolves for up to 48 hr PI. Two infected wolves euthanized 6 mo after the start of the experiment had no lesions, and colonies of B. abortus were isolated from thymus and most major lymph nodes. The other two infected wolves euthanized 12 mo after the start of the experiment had no lesions, and smaller numbers of brucellae were recovered from fewer lymph nodes compared with the wolves killed 6 mo earlier. The sporadic excretion of very small numbers of brucellae by the wolves was insignificant when compared with the infective dose for cattle. Brucella abortus, brucellosis, Canis lupus, pathogenesis, serology, wolf.     

Distinct cycling CD4(+)- and CD8(+)-T-cell profiles during the asymptomatic phase of simian immunodeficiency virus SIVmac251 infection in rhesus macaques

Elevated CD4 T-cell turnover may lead to the exhaustion of the immune system during human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) infections. However, this hypothesis remains controversial. Most studies of this subject have concerned the blood, and information about the lymph nodes is rare and controversial. We used Ki67 expression to measure cycling T cells in the blood and lymph nodes of uninfected macaques and of macaques infected with a pathogenic SIVmac251 strain or with a nonpathogenic SIVmac251Deltanef clone. During the asymptomatic phase of infection, the number of cycling CD8(+) T cells progressively increased (two- to eightfold) both in the blood and in the lymph nodes of macaques infected with SIVmac251. This increase was correlated with viral replication and the progression to AIDS. In contrast, no increases in the numbers of cycling CD4(+) T cells were found in the blood or lymph nodes of macaques infected with the pathogenic SIVmac251 strain in comparison with SIVmac251Deltanef-infected or healthy macaques during this chronic phase. However, the lymph nodes of pre-AIDS stage SIVmac251-infected macaques contained more cycling CD4(+) T cells (low baseline CD4(+)-T-cell counts in the blood). Taken together, these results show that the profiles of CD4(+)- and CD8(+)-T-cell dynamics are distinct both in the lymph nodes and blood and suggest that higher CD4(+)-T-cell proliferation at the onset of AIDS may lead to the exhaustion of the immune system.     

Kikuchi's histiocytic necrotizing lymphadenitis. Diagnosis by fine needle aspiration

Two cases of Kikuchi's histiocytic necrotizing lymphadenitis diagnosed by fine needle aspiration (FNA) of enlarged lymph nodes are reported. The FNA smears contained randomly activated lymphoid cells, necrotic debris, karyorrhectic cells and prominent histiocytes, suggesting the presence of reactive lymph nodes. The true nature of the lesions was evident from the examination of cell block sections prepared from tissue fragments in the aspirates, which preserved the architectural relationships of the different cell types. The same patterns were found in retrospectively and subsequently examined excised lymph nodes from these cases. The differential diagnosis of this entity, which may simulate a malignant lymphoma because of the presence of large numbers of activated lymphoid cells, is discussed and the value of preparing FNA cell blocks is emphasized. Though this rare benign disease may be suspected clinically in the more typical cases, such as young women with cervical lymphadenopathy, fever, neutropenia and otherwise excellent condition, the diagnosis cannot be made without a lymph node biopsy, which FNA may be able to provide in some instances.     

Antigen modulation of the immune response. V. Generation of large memory cells in antigen draining lymph nodes.

We have studied the distribution of memory B cell subpopulations by using 1g velocity sedimentation and adoptive transfer. When the non-antigen-draining mesenteric lymph nodes were examined 4 weeks after intraperitoneal immunization with DNPBGG, large memory cells were present in only very low numbers. However, when the draining parathymic nodes were removed, a significant enrichment of large memory cell activity was seen. When these results were corrected for the cell yields in each 1g separated fraction we found that 59% of the total memory cells were small, 36% medium and 5% large in the mesenteric lymph node preparations and 40% were small, 46% medium and 14% large in the parathymic lymph node suspensions. When popliteal lymph nodes were removed after footpad immunization, 32% of the total memory cell activity was in the small cell fraction while 49% was in the medium fraction and 18% in the large cell fraction. Control experiments were also run to show that the shift in the velocity sedimentation profile of the various memory cell populations was not an artifact of the adoptive transfer system nor a result of selective antigen triggering.From these results it would appear that the size distribution of memory cells depends upon the source of cells studied, large memory cells being found predominantly only in lymph nodes draining the site of antigen injection. Since the large memory cells can also be found in the thoracic duct lymph after footpad immunization but not after intraperitoneal immunization, it is suggested that the larger cells can circulate to other lymphoid tissues but cannot recirculate.     

Progression of armed CTL from draining lymph node to spleen shortly after localized infection with herpes simplex virus 1.

We have examined the generation of CTL immunity immediately after localized footpad infection with herpes simplex virus 1 (HSV-1) using three coordinated in vivo T cell tracking methodologies. Tetrameric MHC class I containing the immunodominant peptide from HSV-1 glycoprotein B (gB) showed that after infection the proportion of Ag-specific T cells peaked at day 5 within draining popliteal lymph nodes and 2 days later in the spleen. Preferential expression of the activation marker CD25 by tetramer-positive cells in draining popliteal nodes but not spleen suggested that gB-specific T cells were initially activated within the lymph node. In vivo cytotoxicity assays showed that Ag-specific effector cells were present within the draining lymph nodes as early as day 2 after infection, with a further 2-day lag before detection in the spleen. Consistent with the very early arming of effector CTL in the draining lymph node, adoptive transfer of CFSE-labeled gB-specific transgenic T cells showed that they had undergone one to four rounds of cell division by day 2 after infection. In contrast, proliferating T cells were first detected in appreciable numbers in the spleen on day 4, at which time they had undergone extensive cell division. These data demonstrate that HSV-1-specific T cells are rapidly activated and armed within draining lymph nodes shortly after localized HSV-1 infection. This is followed by their dissemination to other compartments such as the spleen, where they further proliferate in an Ag-independent fashion.     

Immune response induced by airway sensitization after influenza A virus infection depends on timing of antigen exposure in mice

To study which phase of viral infection promotes antigen sensitization via the airway and which type of antigen-presenting cells contributes to antigen sensitization, BALB/c mice were sensitized by inhalation of ovalbumin (OA) during the acute phase or the recovery phase of influenza A virus infection, and then 3 weeks later animals were challenged with OA. The numbers of eosinophils and lymphocytes, the amounts of interleukin-4 (IL-4) and IL-5 in the bronchoalveolar lavage fluid, and the serum levels of OA-specific immunoglobulin G1 (IgG1) and IgE increased in mice sensitized during the acute phase (acute phase group), while a high level of gamma interferon production was detected in those sensitized during the recovery phase (recovery phase group). In the acute phase group, both major histocompatibility complex class II molecules and CD11c were strongly stained on the bronchial epithelium; in the recovery phase group, however, neither molecule was detected. OA-capturing dendritic cells (DCs) migrated to the regional lymph nodes, and a small number of OA-capturing macrophages were also observed in the lymph nodes of the acute phase group. In the recovery group, however, no OA-capturing DCs were detected in either the lungs or the lymph nodes, while OA-capturing macrophages were observed in the lymph nodes. These results indicate that the timing of antigen sensitization after viral infection determines the type of immune response.     

Motheaten, an immunodeficient mutant of the mouse. I. Genetics and pathology.

A new recessive mutation, motheaten (me), is on chromosome 6, 21.9 +/- 4.3 recombination units distal to white (Miwh). Mice homozygous for the new mutation have neutrophilic lesions of the skin beginning as early as day 1, and pneumonitis with many macrophages in the alveoli as early as day 3. They suffer high mortality from birth onward and none has survived longer than 8 weeks. The lymph nodes may be enlarged, but the thymus, Reyer's patches, and lymphatic tissue of the spleen are much reduced in size. Lymph nodes, spleen, and Peyer's patches lack lymphatic nodules. The lymph nodes and spleen contain many plasma cells. There are increased numbers of neutrophils and monocytes in the peripheral blood, and increased numbers of neutrophils in bone marrow at the expense of red cell precursors. Hematopoietic tissue in the spleen is increased and appears more active than normal. Motheaten mice appear to have an immune deficiency beginning very shortly after birth.     

Cutting edge: egress of newly generated plasma cells from peripheral lymph nodes depends on beta 2 integrin

During humoral immune responses, naive B cells differentiate into Ab-secreting plasma cells within secondary lymphoid organs. Differentiating plasma cells egress from their sites of generation and redistribute to other tissues, predominantly the bone marrow and mucosal tissues. In this study, we demonstrate that within peripheral lymph nodes newly generated plasma cells localize to medullary cords which express the beta(2) integrin ligand ICAM-1. In beta(2) integrin-deficient mice plasma cells accumulate inside the lymph nodes, resulting in severely reduced plasma cell numbers in the bone marrow. Since plasma cells isolated from beta(2) integrin-deficient animals migrate efficiently into the bone marrow when transferred i.v., our findings provide profound evidence that beta(2) integrins are required for the egress of plasma cells from peripheral lymph nodes.     

Maturation and trafficking of monocyte-derived dendritic cells in monkeys: implications for dendritic cell-based vaccines

Human dendritic cells (DC) have polarized responses to chemokines as a function of maturation state, but the effect of maturation on DC trafficking in vivo is not known. We have addressed this question in a highly relevant rhesus macaque model. We demonstrate that immature and CD40 ligand-matured monocyte-derived DC have characteristic phenotypic and functional differences in vitro. In particular, immature DC express CC chemokine receptor 5 (CCR5) and migrate in response to macrophage inflammatory protein-1alpha (MIP-1alpha), whereas mature DC switch expression to CCR7 and respond exclusively to MIP-3beta and 6Ckine. Mature DC transduced to express a marker gene localized to lymph nodes after intradermal injection, constituting 1.5% of lymph node DC. In contrast, cutaneous DC transfected in situ via gene gun were detected in the draining lymph node at a 20-fold lower frequency. Unexpectedly, the state of maturation at the time of injection had no influence on the proportion of DC that localized to draining lymph nodes, as labeled immature and mature DC were detected in equal numbers. Immature DC that trafficked to lymph nodes underwent a significant up-regulation of CD86 expression indicative of spontaneous maturation. Moreover, immature DC exited completely from the dermis within 36 h of injection, whereas mature DC persisted in large numbers associated with a marked inflammatory infiltrate. We conclude that in vitro maturation is not a requirement for effective migration of DC in vivo and suggest that administration of Ag-loaded immature DC that undergo natural maturation following injection may be preferred for DC-based immunotherapy.