Expression of the Protein with Molecular Weight 104-110 kDa by Normal and Malignant Human B Lymphoid Cells

In this paper we present the results of the distribution of a cell surface protein with molecular weight 104-110 kDa (p104-110) detected by monoclonal antibody made in our laboratory. The protein is expressed by a number of cell lines belonging to B lymphoid cells, but not to the other blood cell lineages. In healthy donors the expression of p104-110 is restricted to a minor population of human peripheral blood mononuclear cells shared by both CD20(+) and CD20(-) subpopulation. No expression of p104-110 has been found on resting and activated T cells as well as on monocytes and polymorphonuclear cells. FACS analysis of mononuclear cells derived from normal human bone marrow has revealed the presence of p104-110 on committed CD34(-); CD38(+) mononuclear cell subset that composes only the minor part of mature CD20(+) B cells being mostly CD20 negative. Furthermore, CD19(+)CD5(+)CD20(-) malignant cells derived from the patients with chronic lymphoid leukemia express p104-110 at high level. Similarly, it has been shown that some patients with malignant non-Hodgkin's lymphomas can have the increased contents of CD20(+) cells bearing that surface antigen. Possible associations of p104-110 expression on human B lymphoid cells with their differentiation and activation are discussed.