A novel activation induced lymphocyte surface antigen, 90.12, is also expressed on apoptotic cells.

We describe a monoclonal antibody, mAb 90.12, which recognizes a novel activation induced lymphocyte surface antigen. Flow cytometric analysis of normal tissues shows the antigen to be expressed on higher percentages of B lymphocytes in the bone marrow than in the spleen and the lymph node. Similarly, the 90.12 antigen is expressed on higher percentages of thymocytes than peripheral T cells. MAb 90. 12 immunoprecipitates three proteins with a molecular weight of 12-18 kDa which are not linked to the membrane by phosphotidylinositol. Expression of the 90.12 antigen is increased on activated B cells and the extent of upregulation varies with the stimulus. Lipopolysaccharide (LPS) stimulation results in expression on most B cells, while expression is upregulated on only a subset of B cells stimulated with anti-immunoglobulin M (IgM), interleukin(IL)4 and IL5. Finally, we show that 90.12 antigen expression is also increased on apoptotic cells.

Murine immune response to Neisseria meningitidis group C capsular polysaccharide: analysis of monoclonal antibodies generated in response to a thymus-independent antigen and a thymus-dependent toxoid conjugate vaccine.

Antibody (Ab) responses to polysaccharides (PSs) such as Neisseria meningitidis group C PS (MCPS) are characterized as being thymus independent (TI) and are restricted with regard to clonotype and isotype expression. PS conjugated to proteins, e.g., MCPS coupled to tetanus toxoid (MCPS-TT), elicits a thymus-dependent (TD) response. In order to understand the influence of the form of a vaccine (TI versus TD) on the Ab repertoire, we generated monoclonal antibody (MAb) panels from mice immunized and boosted with MCPS or MCPS-TT in different ways. The panels of MAbs were examined for isotype, fine specificity, affinity, and V(H) gene family usage. The use of MCPS-TT resulted in a shift in the isotype from immunoglobulin M (IgM) and IgG3 elicited in response to the MCPS to primarily IgG1. This isotype shift was accompanied by a change in the fine specificity of the response to the conjugate compared to that of PS. New fine specificities and increased affinity were observed in response to the TD antigen (Ag). Dot blot and Northern analyses of MCPS MAbs revealed that V(H) gene family usage is dominated by V(H)J558, used by 23 of 39 MAbs. V(H)3609 was seen in three MAbs of restricted fine specificity. V(H)Q52, V(H)7183, and V(H)VGAM3-8 were seen in more than one MAb across these panels, while V(H)10 and V(H)X24 were detected only once in response to the TI-2 Ag. All MAbs in the panels utilized kappa light chains, and all functional J(kappa) genes were expressed.