A NOVEL INTERNAL ANTIGEN WHICH DISTINGUISHES GERMINAL CENTER CELLS FROM OTHER B-CELL TYPES

A new monoclonal antibody, 4KB51, is described which labels the majori ty of B cells in blood and in mantle and marginal zones but not germin al centre lymphocytes or plasma cells. Antibody 4KB51 also stains mono cytes, neutrophils and the majority of T cells. It recognizes an intra cellular antigen of 160,000 MW (unreduced) and 68,000 MW (reduced). An tibody 4KB51 labels the tumour cells in all cases of hairy cell leukae mia and in four of the 16 cases of centrocytic B-cell lymphoma studied . No labelling of the other lymphomas (114 cases) or lymphoid leukaemi as (13 cases) tested was seen. Antibody 4KB51 may be of value in defin ing B-cell subsets and in the differential diagnosis of hairy cell leu kaemia and centrocytic lymphomas. The pattern of reactivity of 4KB51 s uggests that its target antigen may play a functional role, possibly i nvolved in lymphocyte homing.