B lymphocyte differentiation in the rat: production and characterization of monoclonal antibodies to B lineage-associated antigens

Dendritic cells and class II MHC expression on thyrocytes during the autoimmune thyroid disease of the BB rat

The BB rat is a well-established model for spontaneous thyroid autoimmune disease. Since antigen presentation in thyroid autoimmunity is still a matter of debate, we studied the presence of antigen-presenting dendritic cells in the thyroid of the BB/O rat during the development of the disease in relation to the presence of other leucocytes and the aberrant expression of class II MHC determinants by thyrocytes. Thyroid glands, as well as thyroid-draining lymph nodes, were investigated in enzyme histochemistry and immune histochemistry. The appearance of anti-colloid antibodies in the circulation at 6 weeks of age was accompanied by an increase in the weight of the thyroid-draining cervical lymph nodes, which contained many anti-thyroglobulin-producing plasma cells. The only noteworthy event in the thyroid gland in this early stage of the disease was an increase in the number of dendritic cells. T cells, B cells, and plasma cells were virtually absent from the thyroid, and thyrocytes were invariably negative for class II MHC determinants. Only after 18 weeks of age, when large accumulations of dendritic cells, B lymphocytes, and T lymphocytes were seen in 40% of the BB thyroids, could some class II MHC positive thyroicytes be observed. At this stage the thyroid also contained some anti-thyoglobulin-producing plasma cells. Our observations suggest that dendritic cells play a role in antigen presentation in the early stages of the thyroid autoimmune response.

In rat B lymphocyte genesis sixty percent is lost from the bone marrow at the transition of nondividing pre-B cell to sIgM+ B lymphocyte, the stage of Ig light chain gene expression

The cycling B precursor cells in rat bone marrow (BM) that carry the B220 antigen and no surface Ig daily produce 780 million new cells. The pool of recirculating B lymphocytes in the rat, however, renew at a rate of only about 40 million cells/day. To analyze at which stages in B lymphocyte genesis the cell loss occurs, we identified post-mitotic cells in the rat BM B lineage, and determined their renewal rates. We used 5-bromo-deoxyuridine (BrdUrd) to label DNA-synthesizing cells, identifying incorporated BrdUrd with the mouse monoclonal antibody BU-1. B lineage cell subsets were identified by the markers HIS24 antigen (rat B220), terminal deoxynucleotidyl transferase (TdT), Ig mu heavy chain, and complete Ig. By use of double and triple immunocytology, we determined the extent of BrdUrd incorporation in the various B lineage compartments [HIS24+TdT-Ig-, TdT+, cytoplasmic mu chain (c mu)+ surface (s) IgM- pre-B, sIgM+ B]. Both sIgM+ B lymphocytes and all B precursors with cell diameters less than 11-12 microns were virtually devoid of DNA synthesis, as indicated by S-phase indices below 2%. In contrast, S-phase indices of large B precursors ranged between 43%-66%. We established the renewal rates of nondividing BM B lineage cells by placing osmotic minipumps containing BrdUrd subcutaneously in the flank of rats. The nondividing BM B lineage cells all renewed rapidly at rates between 2.4% and 5.6%/h, representing average half-lives of 29 to 12 h. In absolute numbers, the renewal/day/whole body BM was 165 X 10(6) for sIgM+ B lymphocytes, 422 X 10(6) for small c mu+ sIgM- pre-B cells, 89 X 10(6) for small TdT+ cells and 35 X 10(6) for small HIS24+TdT-Ig- cells. Assuming that recirculating B lymphocytes in the periphery are the descendants of BM sIgM+ B lymphocytes, which in their turn are the progeny of small pre-B cells, the renewal data indicate the following. Of the 165 million potentially available BM B lymphocytes, only 40 million cells become incorporated in the pool of recirculating B lymphocytes, representing a loss of 75%. BM B lymphocytes, in turn, use only (165/422 X 100% = ) 40% of the potential output from their immediate precursors. The 60% loss that occurs here may reflect the extent of aberrant Ig light chain gene rearrangement in normal B lymphocyte genesis.(ABSTRACT TRUNCATED AT 400 WORDS)

A diminished adherence of blood lymphocytes of patients with thyroid autoimmune disease to high endothelial venules in the thyroid and the thyroid-draining lymph nodes

The function of high endothelial venules (HEVs), present in the T-cell area of lymphoid tissue is to attract lymphocytes to secondary lymphoid organs ("homing"). In Graves' disease, sporadic goitre and lymphocytic thyroiditis HEVs develop in the thyroid. To study the "homing" of peripheral blood lymphocytes (PBL) of healthy individuals and thyroid patients to the thyroid area we studied the adherence of PBL of such individuals to HEVs present in Hashimoto's goitres and to HEVs in thyroid draining lymph nodes. A modification of the in vitro "homing assay" described by Stamper and Woodruff (J Exp Med 144: 823) was used. The number of PBL of patients with Graves' disease which adhered to thyroidal and thyroid-draining lymphnode HEVs was significantly (p less than or equal to 0.001, Wilcoxon test) less than that of healthy control PBL's; in the case of thyroid HEVs 12 (mean, sd 8, n = 18) patient lymphocytes adhered to 35 HEVs vs 19 (mean, sd 7, n = 16) healthy control lymphocytes; in the case of thyroid lymphnode HEVs 20 (mean, sd 12, n = 15) patient lymphocytes adhered vs 35 (mean, sd 9, n = 9) healthy control lymphocytes. PBL of a few sporadic goitre (n = 5) and atrophic lymphocytic thyroiditis (n = 2) patients also showed a diminished adherence to thyroidal HEVs. We also studied the homing capability of lymphocyte suspensions isolated from the thyroid glands of three Graves' disease patients; these infiltrated cells showed a normal adherence pattern to thyroidal HEVs. We favour the idea that the data should be explained by a redistribution of lymphocytes possessing "thyroid-specific-homing-receptors" from the circulation to the thyroid area in patients with thyroid autoimmune disease.

The evolution of B-cell clones

This chapter identifies three forms of B-cell memory: (a) B blasts which characterize the established stage of the follicular response to TD antigens, (b) recirculating memory B cells, and (c) non-recirculating memory B cells of the marginal zones of the spleen and equivalent areas of other secondary lymphoid organs. The follicular B blasts show sustained proliferation driven by small amounts of antigen bound to FDCs. The probable relationships between these cells is summarized diagrammatically in Fig. 4. It is probable that follicular B blasts generate both the recirculating and marginal zone memory cells. The chapter by Gray and Leanderson in this volume cites data which indicate that the recirculating memory pool is not sustained for more than a few weeks in the absence of antigen. Data leading to the same conclusion for marginal zone memory B cells is set out in Sect. 5.1 of this chapter. Marginal zone memory B cells do not appear to move spontaneously to follicles for periodic renewal. They will only leave the marginal zone if a fresh supply of antigen reaches them in that site. Recirculating B cells are able to respond to antigen already held on FDCs. It is not known if they are able to displace B blasts of equivalent affinity for antigen which already occupy antigen-holding sites on FDCs. This could be a mechanism by which B blasts with high antigen affinity produced in one follicle could displace blasts of lower affinity in other follicles. Little is known of the factors which regulate the numbers of marginal zone and recirculating follicular memory B cells. In responses to hapten-protein conjugates, hapten-binding cells may approach 10% of marginal zone B cells but comprise well under 1% of recirculating follicular cells. The numbers of these memory cells do not increase if the recirculating pool of lymphocytes is depleted, indicating that the factors which regulate the number of memory B cells are independent of those which regulate the total size of the recirculating B-cell pool. A depleted peripheral B-cell pool can only be fully reconstituted by recruitment of newly produced virgin B cells. Data cited in Sect. 5.2 support the concept that this recruitment is at least partially independent of antigen-driven B-cell proliferation. Consequently, substantial proportions of the peripheral B-cell pools are likely to be either virgin cells or cells which have been recruited by antigen or anti-idiotype without entering cell cycle.(ABSTRACT TRUNCATED AT 400 WORDS)

Immigration of thoracic duct B lymphocytes into established germinal centers in the rat

Immigration of B lymphocytes into established germinal centers in the rat was studied by transferring genetically marked thoracic duct B cells to non-irradiated congenic hosts at various times between 3 days before and 6 days after host immunization. Seven days after host immunization, the distribution of donor B cells to lymph node germinal centers (relative to their distribution to non-germinal center lymph node areas) was measured by two-color flow cytometry in which (a) donor and host B cells were distinguished by their Ig kappa chain allotypes, and (b) germinal center B cells were distinguished by their lack of labeling with the monoclonal antibody HIS22. Thoracic duct B cells from long-term antigen-primed rats were found to immigrate into host germinal centers much better than B cells from unprimed donors. This effect was antigen specific: primed B cells only immigrated well into host germinal centers induced by the priming antigen. Although B cells localized in germinal centers most efficiently when injected before immunization, specifically primed donor B cells injected after immunization were still found to be at least as evenly distributed to germinal centers as to other lymph node areas, whereas unprimed B cells transferred after immunization localized poorly in host germinal centers. These findings are discussed in light of recent suggestions that memory B cell clones are maintained by continued antigenic stimulation within secondary lymphoid follicles.

The heterogeneity of the reticulum of rat peripheral lymphoid organs identified by monoclonal antibodies

We have developed a panel of six monoclonal antibodies, ED10-ED15, directed against reticular cells in peripheral lymphoid organs. Immunohistochemistry revealed prominent differences between these antibodies with regard to their tissue distribution in lymphoid and non-lymphoid organs. Furthermore, the determinants recognized by ED10-ED13 were found to be differentially expressed by reticular cells occupying the various specialized compartments present in peripheral lymphoid organs. The reactivity patterns of these antibodies observed during the ontogenetic development of the spleen suggest that they recognize differentiation antigens expressed by reticular cells. In contrast, ED14 and ED15 were found to have a relatively ubiquitous tissue distribution recognizing reticular cells in each compartment, with a constitutive reactivity during splenic ontogeny. The present results indicate that reticular cells form a heterogeneous population within the lymphoid organs.

Biochemical and antigenic characterization of CD45 polypeptides expressed on plasma membrane and internal granules of human neutrophils

The expression of CD45 polypeptides, a phosphotyrosine phosphatase complex specific of leukocytes, has been investigated in both resting and activated neutrophils by using anti-CD45 monoclonal antibodies (MAb) which specifically recognize different polypeptide components of the CD45 molecular complex. Polypeptides of 180 and 130-150 kDa were equally precipitated by either a conventional CD45 MAb recognizing an antigenic determinant shared by the four CD45 glycoproteins (220, 205, 190 and 180 kDa) or by the anti-180 kDa UCHL1 MAb. These polypeptides were overexpressed on neutrophil plasma membranes after degranulatory stimulation. Conversely, neither the anti-220 kDa CD45R nor anti-220/205/190 kDa MAb reacted with CD45 molecules from resting or activated neutrophils. Furthermore, permeabilization analysis and comparative immunoprecipitation studies with different anti-CD45 MAb from fractions enriched in various neutrophil granules revealed that CD45 polypeptides (180 and 130-150 kDa) from internal granules are antigenic and biochemically identical to those expressed on plasma membrane.

Immunohistological localization and characterization of FITC-labelled lymphocytes. A rapid and inexpensive method for studying migration

Immunohistochemical methods are described for the detection and characterization of fluorescein isothiocyanate (FITC)-labelled lymphocytes on cryostat sections using an anti-FITC antibody. As a model, the localization of thoracic duct lymphocytes (TDL) in the rat spleen was examined at three time intervals. The kinetic patterns observed clearly differed between the four splenic compartments examined, namely: the red pulp, the marginal zone, the periarteriolar lymphatic sheath (PALS) and the follicle. Furthermore, the subset composition of the immigrant lymphocytes was determined by two colour immunohistochemical staining, which permitted simultaneous detection of the FITC label and surface markers. The results suggest that this method is a fast, easy and inexpensive approach to studies of lymphocyte migration.

Surface phenotype of rat bone marrow-derived mononuclear phagocytes

Utilizing a panel of currently available monoclonal antibodies, the surface phenotype of a pure population of resting rat bone marrow-derived mononuclear phagocytes (BMM phi) was analyzed by means of flow cytometry. The present work provides an extensive list of surface markers expressed by BMM phi and also outlines advantages and limitations of flow cytometric analysis of this cell type. The results show that the majority of surface markers considered to be expressed selectively by T lymphocytes, such as Thy-1, CD2 and CD5 antigens, leukosialin (W3/13), or an alloantigen of peripheral T cells, are not expressed by BMM phi. On the other hand, the CD8 antigen and the leukocyte common antigen recognized by MRC OX-33, considered to represent specific markers of cytotoxic T cells and/or peripheral B cells, are expressed on a variable, often considerable proportion of BMM phi. Monoclonal antibodies W3/25, MRC OX-35, and MRC OX-38, directed against epitopes on the CD4 molecule, labeled a variable proportion of BMM phi. Among the 39 monoclonal antibodies examined, none appeared to recognize an epitope which is expressed selectively by mononuclear phagocytes.

A major peritoneal reservoir of precursors for intestinal IgA plasma cells

Studies presented examine the origin of IgA plasma cells in B lineage chimeric mice constructed by reconstituting lethally irradiated mice with a mixture of syngeneic bone marrow cells and peritoneal cells from Ig heavy chain allotype congenic donors. In these mice, essentially all B cells in spleen and Peyer's patches are derived from the bone marrow donor; however Ly-1 B lineage cells which have been mainly detected in the peritoneum are derived from the peritoneal cell donor. Surprisingly, roughly half of the IgA plasma cells in the lamina propria of the gut are also derived from the peritoneal cell donor, suggesting an important role for peritoneally-derived B cells in the mucosal immune response.