The Expression of a Human B‐Lymphocyte Antigen and Surface Membrane Immunoglobulin by Lymphoid cells from Patients with Lymphocytic Lymphoma, Multiple Myeloma and Benign Monoclonal Gammapathy

Abstract

Lymphoid cells from patients with lymphocytic lymphoma, multiple myeloma or benign monoclonal gammapathy (BMG) were examined by direct immunofluorescence for the expression of surface membrane immunoglobulin (sIg) and B‐cell antigen defined by a rabbit antiserum against chronic lymphocytic leukaemia lymphocytes. This antiserum has been shown to detect a B‐cell antigen different from Ia‐like antigen. In well differentiated lymphocytic lymphoma, the cells carried the B‐cell antigen as well as one class of heavy and light Ig chain. A circulating monoclonal lymphocyte population was regularly found in the blood although the lymphocyte number was not increased. In multiple myeloma the number of circulating cells carrying mu chains was small, the depression being most pronounced in patients who had been treated with cytostatics. A monoclonal population of lymphocytes expressing the Ig isotype(s) of the M‐component was found in the blood in 6/15 cases and more often in patients with advanced disease. The number of cells with B‐cell antigen agreed fairly well with the number of Ig‐positive cells, indicating that the B‐cell antigen was expressed on normal as well as myeloma‐related lymphocytes. A dissociation of the expression of the antigens was however observed in two cases (one lymphocytic lymphoma, one myeloma) with a large number of cells with B‐cell antigen but a small number of cells with sIg. The B‐cell antigen was usually not detected on the surface membrane of Ig‐containing plasma cells from patients without monoclonal gammapathy or from the majority of patients with BMG but on a varying proportion of myeloma cells. The tentative conclusion is drawn that the B‐cell antigen is a differentiation antigen, which is gradually lost during B‐lymphocyte differentiation but is retained to some extent on myeloma cells as an expression of a lower degree of maturity.

Predominant B‐Lymphocyte Deficiency in a Case with Lymph Node Disease Resembling Angioimmunoblastic Lymphadenopathy

“…Lymphocytes were isolated from heparinized venous blood and examined by direct immunofluorescence as de- scribed earlier (8). B-lymphocytes were identified by staining with TRITC-labelled F(ab'), fragments of goat antihuman Fab (Nordic Immunological Laboratories, Tilburg, The Netherlands) or by FITC-labelled F(ab'), fragments of an anti-CLL serum which was earlier shown to recognize B-cell specific antigen(s) (1).…”