Multiple myeloma: the relationship between CALLA (CD10) positive lymphocytes in the peripheral blood and light chain isotype suppression.

This study describes the presence of small numbers of common acute lymphocytic leukaemia antigen (CALLA, CD10)-positive lymphocytes in the peripheral blood of patients with multiple myeloma. A significant correlation (0.001 less than P less than 0.01) was found between the lack of light chain isotype suppression (LCIS), which is characteristic of progressive myeloma, and the presence of CALLA-positive lymphocytes. Sixty patients with multiple myeloma, four with benign monoclonal gammopathy (BMG) and seven with solitary plasmacytoma (SP) were monitored in this study. Nineteen of the patients with multiple myeloma demonstrated LCIS, of which only three were found to have CALLA-positive lymphocytes. Of the 41 patients with multiple myeloma who did not have LCIS, 20 (49%) had CALLA-bearing lymphocytes. None of the patients with BMG or SP demonstrated LCIS or were found to have CALLA-bearing lymphocytes in their blood. Forty-four of the patients with multiple myeloma were also monitored for serum beta-2-microglobulin (SB2M levels. There was no correlation between the SB2M and either LCIS or CALLA-positivity. Detection of CALLA-positive lymphocytes in the blood of patients with multiple myeloma may be an early marker of the onset of progressive disease. The correlation of CALLA expression on lymphocytes with lack of LCIS provides further evidence for the operation of immunoregulatory systems in these patients.