THE EXPRESSION OF THE B-CELL MARKER MB-1 (CD79A) IN HODGKINS-DISEASE

Recent evidence indicates that membrane-bound immunoglobulin on B lymp hocytes is associated with a molecule which comprises the products of the mb-1 and B29 genes. This molecule is a highly specific marker for B-cells, presumably because of its central functional role in antigen triggering, and has recently been clustered as CD79a at the 5th Leucoc yte Workshop, Recently there has been controversy surrounding reports of B-cell antigen expression by Reed-Sternberg and related cells, and we have therefore studied 108 cases of Hodgkin's disease immunohistoch emically using a novel antibody which detects mb-1 protein in paraffin sections. The results were compared with those achieved using antibod y L26 to detect CD20. The mb-1 protein was present in the neoplastic c ells in all 14 cases of lymphocyte predominance Hodgkin's disease stud ied, and CD20 immunoreactivity was also found in seven of the eight ca ses of this subtype studied. Of the non-lymphocyte predominance cases, 20% (19/94) expressed mb-1 and 30% (20/67) CD20 in the Reed-Sternberg cells, but the cells positive for either of these two markers usually constituted only a very small proportion of the neoplastic population . However, in occasional cases (one of 94 for mb-1 and five of 67 for CD20), more than 50% of the neoplastic cells expressed one or both B-c ell antigens. These results confirm the B-cell origin of the neoplasti c cells in lymphocyte predominance Hodgkin's disease, but they also in dicate that, contrary to our previous study, mb-1 expression may occas ionally be found in what appears, on histological grounds, to be other types of Hodgkin's disease.