Characterization of F21.A, a monoclonal antibody that recognize a leucocyte surface antigen for killer whale homologue to beta-2 integrin.

The specificity of F21.A, a monoclonal antibody raised against bottlenose dolphin leucocytes, was characterized in killer whale on the basis of immunoprecipitation of a protein of 94 kDa, as well as flow cytometric analysis. While minimally expressed on resting cells, F21.

Monoclonal antibodies to lymphocyte surface antigens for cetacean homologues to CD2, CD19 and CD21.

CD2 is a pan-T cell marker, while CD19 and CD21 are important molecules in signal transduction of B lymphocytes. CD19 and CD21 are both present on mature B cells, while CD19 is also present in developing B cells and plasma cells. Monoclonal antibodies (mAbs) against cetacean lymphocyte putative homologues to CD2 (two different antibodies), CD19 and CD21 were characterized.

Characterization of a monoclonal antibody that recognizes a lymphocyte surface antigen for the cetacean homologue to CD45R.

As part of our current efforts to develop assays and reagents to study the immune system of marine mammals, and in view of the effort currently made to develop monoclonal antibodies to cell surface proteins of lymphocyte subsets in different species, the present paper reports on the characterization of a monoclonal antibody against the homologue of CD45R on cetacean lymphocytes. The specificity of this antibody has been characterized on the basis of immunoprecipitation of the antigen it recognized, immunoperoxidase staining on cetacean lymph node and thymus sections, as well as one and two-colour flow cytometric analysis of cetacean peripheral blood mononuclear cells and single-cell suspensions of thymus, lymph node and spleen. Anticetacean CD45R (F21.

The density of the class II MHC T cell receptor ligand influences IFN-gamma/IL-4 ratios in immune responses in vivo.

Activation of CD4+ T cells depends on T cell receptor recognition of MHC class II/peptide and on costimulation provided by CD28/B7. It has been shown that different levels of costimulation can influence T helper cell differentiation into Th1 versus Th2 phenotypes. Similar arguments have been made for different levels of peptide/MHC density on antigen-presenting cells, but to date supportive evidence has only come from in vitro studies.

Thymic cortical epithelium is sufficient for the development of mature T cells in relB-deficient mice.

Thymic development of T lymphocytes progresses as a consequence of both TCR-mediated and non-TCR-mediated interactions between thymocytes and stromal cells. As relB-deficient mice appear to lack thymic medullary epithelium and mature dendritic cells, we studied the effect of this "cortex-only" thymus on T cell development. Two major consequences were observed.

Dendritic-like cells from relB mutant mice.

Mice deficient in the NF-kappa B transcription factor relB appear to have defects in the production of mature dendritic cells, as secondary lymphoid tissues are absent, and spleen cells show a significant loss of antigen presenting function. Moreover, the thymus appears to be impaired in negative selection, and immune responses in vivo are poor. Since dendritic cell precursors such as skin Langerhans cells appear to be normal, we sought information on the nature of the dendritic cell defect in these mice.