CD30(Ki-1) antigen expression in a subset of gastric mucosal plasma cells and in a primary gastric plasmacytoma.

With the use of frozen sections, 24 different monoclonal antibodies (MoAbs), and an indirect peroxidase technique, the antigenic profile of a well-differentiated primary gastric plasmacytoma was obtained. Corresponding to the normal plasma cell, tumor cells were devoid of HLA-D products and B-cell-restricted differentiation antigens CD19, CD20, CD21, CD22, and CD23 while expressing plasma cell-associated CD24 and CD38 molecules and IgA/lambda. The plasmacytoma furthermore reacted with CD30(Ki-1), a reactivity that for this tumor type has not been reported before. Subsequently, normal gastric mucosae affected by all degrees of chronic gastritis were examined. On the basis of serial sections, 5-15% of CD38(OKT10) reactive mucosal plasma cells were observed to also react with CD30(Ki-1). The authors conclude that the CD30 antigen is not only an activation antigen but is also expressed on a subset of terminally differentiated plasma cells.