Journal Article•
Characterization by a monoclonal antibody and functional analysis of a subset of bovine T lymphocytes that express BoT8, a molecule analogous to human CD8.
TL;DR: Fractionation of effector cells generated in an allogeneic mixed leucocyte culture (MLC) demonstrated that cytotoxic cells specific for class I major histocompatibility complex (MHC) antigens reside within the BoT8+ population.
Abstract: Monoclonal antibody (mAb) IL-A17 characterizes a subset of bovine T lymphocytes. IL-A17 recognizes a 34,000-35,000 MW doublet, designated BoT8, which is expressed on the surface of approximately 20% of peripheral blood mononuclear leucocytes (PBM), a subpopulation of lymphocytes in T-dependent areas of lymph nodes and spleen, and about 70% of thymocytes. This molecule is not expressed on B lymphocytes, monocytes/macrophages or granulocytes. Double labelling of PBM showed that the BoT8+ population is distinct from the T lymphocyte subset expressing BoT4. BoT8+ lymphocytes purified with a fluorescence-activated cell sorter (FACS) proliferated poorly in response to mitogenic and alloantigenic stimulation in the absence of exogenous growth factors. IL-A17 had no inhibitory effect on proliferation of PBM to mitogens (Con A and PHA) or alloantigens and no measurable effect on the in vitro generation of cytolytic effector cells. However, in some experiments IL-A17 was found to block partially allospecific cytolytic function mediated by bulk effector cell populations when included in 51Cr-release assays. Fractionation of effector cells generated in an allogeneic mixed leucocyte culture (MLC) demonstrated that cytotoxic cells specific for class I major histocompatibility complex (MHC) antigens reside within the BoT8+ population. Based on these data, and information reported elsewhere on alloreactive bovine T-cell clones, BoT8 is considered to be analogous to CD8 in humans and equivalent molecules in other species.
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TL;DR: The strategies described for identifying and analyzing the specificity of MoAbs demonstrate the feasibility of developing a set of cross reactive MoAbs for identifying homologous molecules in multiple species and delineating their functional and phylogenetic relation.
280 citations
TL;DR: Results indicate that the IL‐A29 and CC15 antibodies define a unique population of CD4−CD8−, γ/δ T cells.
Abstract: In this study, two monoclonal antibodies, IL-A29 and CC15, are described that identify a novel bovine cell surface marker of 215/300 kDa. The antibodies reacted with a discrete population of resting lymphocytes in peripheral blood which, in young animals, constituted about 25% of the mononuclear cells. Thymus, lymph nodes and spleen contained less than 5% positive cells. These cells were negative for surface Ig, a monocyte/granulocyte marker, and the T lymphocyte antigens CD2, CD6, CD4 and CD8. Immunohistological analyses revealed the presence of IL-A29/CC15-positive lymphocytes in the thymic medulla, in the outer cortex of lymph nodes, in the marginal zones of the spleen, in the dermal and epidermal layers of the skin and in the lamina propria of the gut. The IL-A29/CC15+ cells in unfractionated blood mononuclear cells responded in autologous and allogeneic mixed lymphocyte cultures, and when purified they responded to concanavalin A in the presence of recombinant interleukin 2. These observations suggested this population of cells belonged to the T cell lineage. In order to unambiguously define their lineage, cDNA clones encoding bovine T cell receptor (TcR) and CD3 proteins were isolated. Northern blot analyses of IL-A29/CC15+ cell populations and of established cell lines of various lineages demonstrated that they expressed TcR delta and CD3 gamma, delta and epsilon mRNA: TcR alpha was not expressed, whereas only a truncated form of TcR beta mRNA was present. These results indicate that the IL-A29 and CC15 antibodies define a unique population of CD4-CD8-, gamma/delta T cells.
205 citations
TL;DR: In thymus the antibodies defined populations of double-positive, double-negative and single-positive cells that showed a progressive maturation consistent with that described for CD4 and CD8 in other mammalian species, and the functional significance of neutrophil CD4 expression is puzzling in light of the current understanding of the functions of CD4.
Abstract: The characteristics of canine homologues of CD4 and CD8, defined by murine monoclonal antibodies CA13.1E4 (IgG1) and CA9.JD3 (IgG2a) respectively, are described. These antibodies identify mutually exclusive subpopulations of non-B lymphocytes in peripheral lymphoid organs and blood. However, in thymus the antibodies defined populations of double-positive, double-negative and single-positive cells that showed a progressive maturation consistent with that described for CD4 and CD8 in other mammalian species. Furthermore, functional studies clearly associated cytotoxic effector cell function with the subpopulation reactive with CA9.JD3 (CD8). In contrast, proliferation stimulated by allogeneic cells and mitogens was more pronounced in the subpopulation reactive with CA13.1E4 (CD4). Cell and tissue distribution studies revealed that CA13.1E4 stained neutrophils with equivalent intensity to the staining of peripheral T cells. CA13.1E4 precipitated a 60 kD protein from the surface of T cells and highly purified neutrophils under both reducing and nonreducing conditions. CA9.JD3 precipitated a heterodimer of 32 kd and 36 kD under reducing conditions, and a 70 kD protein under non-reducing conditions. The expression of CD4 by canine neutrophils is without precedent in other mammalian species; the functional significance of neutrophil CD4 expression is puzzling in light of the current understanding of the functions of CD4 which include it's role as a receptor for nonpolymorphic regions of MHC class II molecules.
153 citations
TL;DR: This lymphocyte subpopulation has a nonspecific suppressor activity acting on B cell responses either directly or through an effect on T helper cells, suggesting it may be an intraepithelial lymphocyte population with a suppressor function.
Abstract: The effect on certain immune responses of depleting two distinct lymphocyte subpopulations in vivo by inoculating calves with monoclonal antibodies (mAb) was examined. An mAb directed against the BoT4 antigen (the bovine homologue of CD4) effectively removed the BoT4+ lymphocytes from peripheral blood mononuclear cells (PBM). Compared to controls, treated calves showed a reduced antibody response to human O red blood cells and to ovalbumin. PBM prepared from BoT4-depleted animals also had a significantly reduced ability to respond in vitro to the mitogens phytohemagglutinin, concanavalin A and pokeweed mitogen. An mAb directed against a second numerically large bovine lymphocyte subpopulation i.e. BoT2-, BoT4-, BoT8- (CD2-, CD4-, CD8-), that may be homologous to the CD4-, CD8- cells in man and rodents that synthesize the gamma/delta+ T cell receptor, was also used for in vivo depletion. Compared to controls, calves depleted of this subpopulation showed an enhanced antibody response. The proliferative response of PBM to pokeweed mitogen was also significantly increased but responses to concanavalin A and phytohemagglutinin remained unchanged. The results suggest this lymphocyte subpopulation has a nonspecific suppressor activity acting on B cell responses either directly or through an effect on T helper cells. The non-T4/T8 cells are found extensively in the epithelium and lamina propria of the mucosa of the alimentary tract but not in T cell areas of the lymph nodes, tonsil and spleen. These non-T4/T8 cells may thus be, or contain, an intraepithelial lymphocyte population with a suppressor function.
120 citations
119 citations