A NOVEL CELL-SURFACE PROLIFERATION-ASSOCIATED MARKER EXPRESSED ON T-CELLS AND UP-REGULATED ON GERMINAL CENTER B-CELLS

In this study we present data on a novel cell surface antigen recogniz ed by monoclonal antibody (mAb) VPM30, originally thought to recognize only bovine and ovine sIg(+) B cells from peripheral blood. Here we s how that the antigen, molecular mass 28 kDa, is not only found in B ce ll follicles in frozen sections, but when used on paraffin sections VP M30 specifically stains B cells in the Light zone of germinal centers but not in the mantle or dark zones. In addition we show that the anti gen is also expressed by 90% of T cells after activation, with kinetic s of antigen expression mirroring those of proliferation. By both size and distribution, the antigen appears to be novel, corresponding to n o known cluster of differentiation, and will be of great use in the st udy of ruminant cellular immune responses.