Retention Of Lymphocytes Research Articles

The immunomodulatory compound 2-acetyl-4-tetrahydroxybutyl imidazole causes sequestration of lymphocytes in non-lymphoid tissues.

2-Acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl) imidazole (THI) is an immunomodulatory compound which causes a reversible lymphopenia in mice by an unknown mechanism. In this study, we investigated the whereabouts of cells lost from the blood and the spleen during THI treatment Homing studies following is injection of fluorescently labelled splenocytes into THI-pretreated recipients showed that THI increased labelled cells in the liver, lungs and kidneys of THI-treated mice. Furthermore, the sequestration in the liver occurred just 1.5 h after injection of labelled cells with the increase still being present at 24 h after injection. Microscopic examination of liver sections indicated that fluorescent lymphocytes were clustered within the liver sinusoids in THI-treated mice, possibly associated with endothelial cells. The liver retention of lymphocytes was confirmed by immunohistochemical studies which showed a significant increase of T cells in the liver of THI-treated mice. To determine the subset of lymphocytes which are lost from the spleen and sequestered in non-lymphoid organs, lymphocytes remaining in the spleen after THI treatment were characterized. Our results confirmed that THI reduced B cells, CD4+ and CD8+ T cells and cells expressing CD62L, CD44 and IL-2R in the spleen.

Lymphocyte-fibroblast interactions.

Chronic inflammatory reactions are usually characterized by inflammatory cell accumulation in the extravascular connective tissue. In such sites, inappropriate activation of circulating or resident lymphocytes becomes self-perpetuating and can lead to chronic tissue destruction. In addition to that, the locally infiltrated lymphocytes should have an opportunity to interact directly with fibroblasts composing the connective tissue. The direct interactions of those different cell types seem to play important roles in lymphocyte lodging and retention in such sites. Thus, for clarification of the immunopathogenesis of the chronic inflammatory diseases, including periodontitis, it is important that the molecular mechanisms involved in the heterotypic cell-cell interactions be revealed. In fact, it has been demonstrated that lymphocytes interact with various non-hematopoietic cells, such as epithelial cells and endothelial cells. Regarding interactions with fibroblasts, it has been shown that IFN gamma-stimulated fibroblasts can regulate the proliferative responses of T-lymphocytes both positively and negatively. Furthermore, activated lymphocytes have demonstrated strong binding ability to various fibroblast cell lines. Blocking experiments utilizing monoclonal antibodies specific to various cell adhesion molecules revealed that very late antigen (VLA) integrins, lymphocyte-function-associated antigen (LFA-1)/intercellular adhesion molecule-1 (ICAM-I), CD44/hyarulonate are, at least in part, involved in lymphocyte-fibroblast interactions. In addition, recent findings raised the possibility that the adhesive interactions between lymphocytes and fibroblasts influenced the various cellular functions of each cell type. In fact, it was recently demonstrated that the adhesive interactions stimulated fibroblasts to increase expression of inflammatory cytokine mRNA. These results strongly suggest that fibroblasts are not merely innocent bystanders but actively participate in local inflammatory reactions by directly interacting with locally infiltrated lymphocytes.

Immunoregulatory roles of adhesive interactions between lymphocytes and gingival fibroblasts

Chronic adult periodontitis is usually characterized by inflammatory cell accumulation in the extravascular periodontal connective tissue. In order to reveal how the lymphocyte migration and retention in periodontal lesions is regulated, we have focused on the molecular basis for the adhesive interactions between lymphocytes and human gingival fibroblasts (HGF). In this study, we investigated the involvement of cell adhesion molecules in adhesive interactions between lymphocytes and HGF. We found that activated lymphocytes bound strongly to HGF and VLA integrins, extracellular matrix receptors, play crucial roles in the binding. Interestingly, we first revealed that CD44 molecules (hyaluronate receptor) on lymphocytes also participated in lymphocyte-HGF interactions and that hyaluronate anchored on the surface of HGF functioned as the ligand for CD44. In addition, when HGF were stimulated with inflammatory cytokines such as IL-1, TNF alpha and IFN gamma, the binding avidity between lymphocytes and HGF was significantly increased and the adhesion was mainly mediated by LFA-1/ICAM-1 pathway. We then examined the possibility whether lymphocyte-HGF interaction may cause activation of HGF. When HGF directly interacted with lymphocytes for 3 h, IL-1 beta mRNA expression was clearly increased in HGF. These findings suggested that the adhesive interactions between lymphocytes and HGF was mediated at least by VLA integrins, LFA-1/ICAM-1 and CD44/hyaluronate and that the heterotypic cell-cell interactions could mutually cause intracellular signal transduction.

Distribution of beta 7 integrins in human intestinal mucosa and organized gut-associated lymphoid tissue.

Two alternative integrins involved in mucosal homing (alpha 4 beta 7) or epithelial retention (alpha E beta 7) of lymphocytes were examined in the human gut. The distribution of the beta 7 subunit [monoclonal antibody (mAb) M301] was bimodal in that it was strongly expressed by alpha E beta 7 + cells but weakly by alpha 4 beta 7 + cells. More than 90% of intraepithelial lymphocytes (IEL), including the minor subsets of CD4+, T-cell receptor (TCR) gamma/delta +, and CD3- cells, expressed alpha E beta 7 as did most lamina propria CD8+ (88%) and a fraction (36%) of CD4+ lymphocytes. Conversely, B-lineage cells (CD19+) and macrophages (CD68+) were negative. In gut-associated lymphoid tissue (GALT: Peyer's patches and appendix) only a few (< 5%) cells were positive for alpha E beta 7 (confined to CD8+ lymphocytes and CD11c+ putative dendritic cells). A relatively small fraction of IEL (30-50%) expressed alpha 4 beta 7 (mAb Act-1), while most (70%) lamina propria T and B lymphocytes, blasts, plasma cells and macrophages were positive. In GALT, T lymphocytes expressed similar levels of alpha 4 beta 7 as in the lamina propria whereas relatively few B lymphocytes (< 50%) were positive. Isolated lamina propria CD8+, CD4+, CD19+, and CD38+ cells contained mRNA for alpha 4 and the former three subsets as well as appendix CD8+ cells also for beta 7 while only lamina propria CD8+ cells had mRNA for alpha E. Together, the results suggested that alpha E beta 7 and alpha 4 beta 7 are differentially regulated in inductive sites and effector sites of the human gut. Because lymphoid cells at both sites expressed mainly alpha 4 beta 7, this integrin may be a homing receptor on memory and effector cells bound for lamina propria as well as on naive lymphocytes extravasating in GALT. Conversely, because alpha E beta 7 was mainly expressed by CD8+ cells in epithelium and lamina propria, it was probably induced after extravasation, in agreement with the observation that IEL and a fraction of lamina propria T lymphocytes (mainly CD8+ cells) generally expressed higher levels of beta 7 than most CD4+ and B cells. Also a subset of putative dendritic cells located near the follicle-associated epithelium of GALT expressed alpha E beta 7, perhaps reflecting epithelial interaction during primary immune responses.

The Specificity of Adhesive Interactions between Rat Lymphocytes and Salivary Gland Epithelia

Salivary immune responses depend on localization of immunocytes in salivary glands. We tested effects of anti-adhesion molecule antibodies and several ligand analogs onin vitroadherence of rat thoracic duct lymphocytes (TDL) to parotid and submandibular gland sections. While TDL adherence to both tissues was markedly decreased by anti-L-selectin mAbs, binding ability after removal of L-selectin by chymotrypsin or PMA suggested that other adhesion systems were involved. Integrin involvement in parotid interactions was indicated by inhibitory effects of anti-HEBFPP, LFA-1, ICAM-1, and α4integrin antibodies as well as by the PMA-enhanced adherence. Anti-Thy-1 partially inhibited TDL binding to parotid gland, and anti-CD44 partially inhibited submandibular binding. The majority of salivary gland-bound TDL were sIg+B cells. FACS analysis showed differences in parotid and submandibular endogenous lymphocyte adhesion molecule expression with greater percentages of L-selectin, HEBFPP, α4integrin, LFA-1, ICAM-1, CD44, and Thy-1-positive cells present in parotid gland. While precise roles of known or novel adhesion molecules in salivary gland lymphocyte retention are not clear, these data suggest that selectins (parotid, submandibular), integrins (parotid), Thy-1 (parotid), and CD44 (submandibular), as well as other unidentified molecules, are involved.

The Exit of Lymphocytes and RBCs from the Peritoneal Cavity of Sheep

The purpose of this study was to compare the exit rates and migration pathways of 51Crlabeled lymphocytes from the peritoneal cavity into the blood with those of a non-motile cell population, 111In-RBCs, in order to determine whether lymphocytes actively migrate from the peritoneal cavity. Radiolabeled cells were infused into the peritoneal cavity and multiple samples of lymph draining from the peritoneal cavity and/or blood were obtained, then the animal was sacrificed and various tissues were harvested and assayed for radioactivity. The recovery of 51Cr-lymphocytes from the mesenteric nodes was not significantly different from that of nodes anatomically distant from the cavity, so it is unlikely that large numbers of lymphocytes migrate across the mesothelial lining of the cavity and into the mesenteric lymphatics. However, the caudal mediastinal node contained about 18-fold more 51Cr-lymphocytes and 473 times as many 111In-RBCs, confirming the importance of this node in the drainage of cells and fluid from the cavity. The hepatic node also appears to receive cells directly from the peritoneal cavity. We also calculated the recovery of labeled cells at the. end of the experiment (T = 40 h), and found that the recovery of 51Cr-lymphocytes (3.87 ± 1.29 %ID).in the blood was much lower than that of 111In-RBCs (35.28 ± 5.02 %ID). This difference can be attributed mainly to the traffic of labeled lymphocytes out of the blood rather than the selective retention of lymphocytes within the peritoneal cavity. Cannulation of the caudal mediastinal efferent lymphatic and the thoracic duct, which drain the peritoneal cavity, revealed approximately a 3-fold higher cumulative recovery of 111In-RBCs than 51Cr-lymphocytes over 6 h. However, by 40 h the percentage of labeled RBCs and lymphocytes remaining in the cavity was not significantly different. While 51Cr-lymphocytes may leave the peritoneal cavity at a slower rate than "'In-RBCs, both cell populations appear to exit solely via lymphatic vessels.

Radiolabelled lymphocyte migration in rheumatoid synovitis.

To study the ability of technetium-99m hexamethyl propylene amineoxime (HMPAO) labelled lymphocyte scintigraphy to quantify synovial inflammation, and to analyse the kinetics of lymphocyte retention in the joints of patients with rheumatoid arthritis (RA). After isolation of the lymphocytes, the cells were radiolabelled in vitro with 250 MBq 99mTc-HMPAO. The scans were performed 30 minutes, three hours and 20 hours after injection. An increase of the scintigram signal obtained at 20 hours was associated with a high joint swelling and joint pain score (F test = 3.07, p < 0.002), but not with the radiological score. A positive joint scintigram was predictive of active synovitis. Although the scintigram variation over time did not reach statistical significance, the kinetics of the scintigram signal tended to differ according to the disease duration: in early RA, active arthritis could be clearly imaged as early as 30 minutes, increased at three hours and the signal intensity persisted at 20 hours. In contrast, in long standing disease, the affected joints were imaged at 30 minutes, persisted unchanged at three hours, and the scintigram score decreased significantly at 20 hours. The study shows that 99mTc-HMPAO joint scintigraphy may be used to detect and to localise active rheumatoid arthritis.

Adhesion between epithelial cells and T lymphocytes mediated by E-cadherin and the alpha E beta 7 integrin.

In contrast to sessile cell types, lymphocytes migrate through the vasculature to become diffusely distributed in tissues or organized in lymphoid structures. A complex array of adhesion molecules including selectins, integrins and their counter-receptors mediate lymphocyte homing and migration into tissues and may be constitutively expressed or induced. However, the molecules that mediate the tissue-specific retention of lymphocytes within the parenchyma have not been identified. Along the epithelium at the basolateral surface of enterocytes, intestinal intraepithelial lymphocytes are found. These T cells of the mucosal immune system serve as a model for the tissue-specific compartmentalization of lymphocytes. We investigated whether the localization of these intestinal intraepithelial lymphocytes could be mediated by specific interactions between adhesion molecules expressed selectively on this subpopulation of T cells and tissue-restricted adhesion molecules on epithelial cells. Here we show that heterotypic adhesive interactions between epithelial cells and intraepithelial lymphocytes in vitro are mediated by E-cadherin and the alpha E beta 7 integrin.

Immunopathogenesis of chronic inflammatory periodontal disease: cellular and molecular mechanisms.

Recent studies of the cellular mechanisms involved in chronic inflammatory periodontal disease (CIPD) have contributed significantly to our understanding of the pathogenesis of the disease process. Functional studies have demonstrated polymorphonuclear neutrophil (PMN) chemotactic defects in some 70% of subjects with localized juvenile periodontitis while chemiluminescence data have suggested that peripheral blood PMNs from young subjects with adult periodontitis (AP) may be in a metabolically active state. Further studies have shown that stimulation of PMNs with a number of periodontopathic bacteria resulted in the production of an IL-1 inhibitor suggesting a possible regulatory role for PMNs in CIPD in addition to their established protective role. Most work on the immunoregulation of CIPD has, however, concentrated on T-cells. Recent limit dilution analysis has demonstrated the presence of periodontopathic bacteria-specific T cells in peripheral blood and the involvement and homing of these cells to the local lesions of CIPD is currently the focus of many studies. In animal studies, Actinobacillus actinomycetemcomitans (Aa)-specific T-cell clones home to the gingival tissues where they may exert a protective role. Homing and retention of lymphocytes to and in specific sites is dependent upon the expression of adhesion molecules. Recent data indicate however, that while there are increasing levels of ICAM-1, LECAM-1 and PECAM-1 expression with increasing degrees of inflammation, there are no differences between gingivitis and periodontitis lesions. Cytokine profiles may be related to the role of T-cell clones homing to the gingiva in CIPD.(ABSTRACT TRUNCATED AT 250 WORDS)

The mechanism of white cell reduction by synthetic fiber cell filters

The mechanism of white cell (WBC) retention by synthetic fiber-based WBC filters was studied. Filters were made of nonwoven fleece prepared from polyester, surface-modified polyester, or polypropylene fibers. Human platelet concentrates were filtered through experimental filters consisting of 8 to 54 layers of nonwoven fleece with mean pore sizes from 7.3 to 14.2 microns. Filters made of fleece of smaller pore size removed WBCs less effectively than filters with larger-pore fleece. Retention of lymphocytes and granulocytes gradually dropped to 0 percent as increasing loads were applied to the filters. The maximal retention capacity for these cell types (i.e., the number of cells retained when "saturating" numbers of WBCs were applied) was proportional to the number of layers of filter material used. Platelet retention did not correlate with WBC retention. Depth filtration, rather than mechanical sieving, seems to be the principal means of WBC removal by nonwoven fiber filters. A low initial number of WBCs in the component to be filtered is important for successful WBC filtration.

Intestinal T lymphocytes in the chicken express an integrin‐like antigen

We report the characterization of a molecule recognized on chicken T cells by the murine A19 monoclonal antibody that was generated by immunization with intestinal intraepithelial lymphocytes. Immunofluorescence analysis indicated that both alpha beta and gamma delta T cell subpopulations in the intestine express the A19 antigen, but natural killer cells and B cells do not. The A19-marked T cells were preferentially localized in the intestinal epithelium and less frequently in the underlying lamina propria. T cells appearing in the intestine during embryonic life were A19 negative but acquired the antigen within the first few days after hatching. Although rarely found on cells in non-intestinal tissues at any age, very late expression of the A19 antigen could be induced by concanavalin A stimulation of splenic and circulating T cells. Transforming growth factor beta 1 enhanced this induction of A19 expression. The A19 molecules expressed by intestinal T cells and activated splenic T cells were biochemically identical, consisting of a multi-molecular complex of proteins with approximate M(r) of 205, 145 and 75 kDa under nonreducing conditions and 120, 90 and 28 kDa under reducing conditions. The characteristics of this multimolecular complex and its differential expression suggest that the A19 antigen is a member of the integrin family which may function in the retention of intestinal lymphocytes.

Retention of lymphocytes in the subcapsular sinus of lymph nodes: A physiological event?

This study examined the lymphocyte content of the subcapsular sinus of lymph nodes of diverse anatomical sites, from euthymic and athymic animals of various ages. One unusual feature which prevailed in young euthymic animals consisted of the accumulation of lymphocytes on the outer wall of the subcapsular sinus, following differential patterns with respect to diverse domains or areas of the subcapsular sinus of a node compartment. It is concluded that such an accumulation is due to the retention of lymphocytes on the sinus outer wall. Whether the retention reflects a step in unspecific defence mechanisms, in an immunological reaction pathway, or a transient state of the misfunctioning of lymph-carried cells, is considered. Some findings favor the latter possibility. In this case, retention would be due to a mild form of lymphocyte alteration caused by the emergence of an abnormal milieu in a drained tissue, and conceivably involving mast cell products. Whatever the case, the retention on the outer wall of the subcapsular sinus, instead of on its inner wall, would prevent any hindering of the usual activity of the latter wall.

Quantitative evaluation of rat lymphocyte adsorption on microdomain structured surfaces of poly(2-hydroxyethyl methacrylate)/ polyamine

The adsorption behaviour of rat lymphocytes on poly(2-hydroxyethyl methacrylate)- graft-polyamine (HA) copolymers was evaluated using a newly developed Chromatographic method. The quantity of lymphocyte adsorption can be varied by regulating the polyamine content in the HA copolymer. A remarkable depression in lymphocyte adsorption was observed on the surface of HA copolymer, consisting of 7 wt% of polyamine graft and 93 wt% of poly(2-hydroxyethyl methacrylate) (pHEMA) backbone. Further introduction of a polyamine graft on pHEMA resulted in the increase of lymphocyte retention on the copolymer surfaces. Lymphocytes adsorbed on HA copolymer surface retained their original round shape. Detailed analysis of the chromatogram showed that interaction of lymphocytes with HA copolymer was very much weaker than that with homopolymer of pHEMA or polyamine.

Alterations in lymphocyte recirculation within ultraviolet light-irradiated mice: Efferent blockade of lymphocyte egress from peripheral lymph nodes

Ultraviolet irradiation (uvR) has been demonstrated to have profound effects on many functions of the immune system. In particular, exposure to this physical agent can alter the tissue distribution and function of a number of immunologically active cell types, even at sites remote from direct uvR exposure. The present investigation demonstrates that uvR exposure of mice induces an efferent blockade of lymphocyte egress from the peripheral lymph nodes which drain the irradiated skin, resulting in marked retention of lymphocytes. In vivo studies of this efferent blockade established that the condition appeared similar in mechanism to that induced by the administration of poly-inosinic:poly-citidylic acid, murine interferon α β and specific antigen. We were able to establish that a common mechanism in the genesis of an efferent lymphatic blockade may involve prostaglandin biosynthesis. The potential contribution of efferent blockade to the development of systemic suppression of contact hypersensitivity induced by uvR exposure is discussed.

RESOLUTION AND RELAPSE OF OSTEOPETROSIS IN MICE TRANSPLANTED WITH MYELOID TISSUE OF VARIABLE HISTOCOMPATIBILITY

Osteopetrotic microphthalmic mice (mi/mi) were treated by injections of suspensions of myeloid tissue, newborns i.p., and weanlings i.v. Donated syngeneic material effected permanent cure of oteopetrosis provided that the dose was large enough (10(8) cells of bone marrow). H-2-compatible allogeneic bone marrow was initially as effective, but relapse ensued in immunocompetent mice. H-2-incompatible marrow was ineffecitve except in one set of newborn tolerant mice. Total body X-radiation in sublethal doses to recipients allowed permanent cure with H-2-compatible, and, in one circumstance, with H-2-incompatible marrow in smaller doses. The best results were obtained after lethal irradiation and the smaller dose of marrow. Results were checked by chromosome assay demonstrating that cure or relapse was correlated with permanent take or rejection, respectively, of a transplant in a recipient's bone marrow. Retention of donor lymphocytes alone was not associated with effective bony resorption; the candidate cell line for effectiveness remains the haematopoietic stem cell-monocyte-tissue phagocyte.

Retention in glass bead columns as a measure of leucocyte adhesiveness. I. Influence of sample size and erythrocyte sedimentation.

Erythrocyte sedimentation significantly influenced test results when leucocyte retention in glass bead columns was used as a measure of leucocyte adhesiveness. In blood with elevated ESR, this influence was especially evident. Erythrocyte sedimentation highly increased leucocyte retention in vertical columns with a downward flow, whereas in slightly tilted columns with an upward flow, the retention was reduced. The error in measurements caused by erythrocyte sedimentation could be corrected by means of the haematocrit values in samples and eluates. Correction was better for results obtained with slightly elevated than with vertical columns. The granulocyte retention rates increased with increasing sample size, whereas lymphocyte retention remained constant.

CHANGES IN MIXED LYMPHOCYTE CULTURE-REACTIVE LYMPHOCYTES FOLLOWING ALLOIMMUNIZATION OF SINGLE LYMPH NODES IN SHEEP

When an "isolated" single lymph node is challenged with irradiated allogeneic lymphocytes, there is a change in the reactivity of the lymphocytes flowing out of the node when they are cultured in vitro in unidirectional mixed lymphocyte cultures (MLC) against the immunizing lymphocytes. These changes in the reactivity of the recipient lymphocytes are shortlived, follow a set time sequence in relation to the cell traffic changes accompanying the immune response, are the property of small lymphocytes and not blast cells, are exhibited by surface Ig-negative cells, and they are specific for the donor lymphocytes. It is suggested that antigen causes the selective retention of antigen-specific lymphocytes within the stimulated node followed by the proliferation and differentiation of large numbers of antigen-specific cells, which then leave the lymph node as small lymphocytes.

Role of macrophages in the mechanism of specific retention of sensitized lymphocytes in lymph glands containing antigen

The role of macrophages in the phenomenon of specific retention of antigen-activated. lymphocytes in lymph glands containing the same antigen was investigated. Injection of peritoneal macrophages, phagocytosing sheep's red cells (as well as of the red cells alone) was found to cause specific retention of lymphocytes in the regional lymph glands. Preliminary treatment of the antigen-loaded macrophages with antierythrocytic serum reduced the retention of lymphocytes. It is postulated that lymphocytes are fixed by means of receptors on their surface to the membrane of macrophages, into which antigen molecules are incorporated.

Investigation of specific retention of lymphocytes proliferating under the influence of an antigen in mouse lymph glands containing the same antigen

Investigation of specific retention of lymphocytes proliferating under the influence of an antigen in mouse lymph glands containing the same antigen

Alterations in Lymphocyte Populations in Tumorigenesis

Abstract Studies have been conducted of the migration of 51Cr-labeled lymph node cells into the lymphoid tissues of mice inoculated with the Moloney sarcoma virus. Significant numbers of labeled cells were trapped in the draining lymph nodes and spleens of tumor-bearing mice. The kinetics of lymphocyte trapping correlated with the cycle of growth and spontaneous regression which is characteristic of this tumor in healthy mice. Trapping first occurred after injection of the virus and maximal retention of lymphocytes corresponded to the time of tumor regression.