Recognizes a protein of 74kDa, identified as CD84 (Workshop V; Code A085, C057). It is expressed on mature B cells and on B-cell lines, including pre-B-cell lines, but not on plasma cell lines. Immunohistochemical studies demonstrated that CD84 strongly expressed on tissues macrophages. CD84 is also highly expressed on platelets and, at low levels on peripheral blood T cells. It is a highly N-glycosylated protein and belongs to immunoglobulin superfamily. It may play a role in leukocyte activation.