Clonal rearrangement of the beta-T cell receptor gene in multiple myeloma

Because clonal rearrangements of the beta-T cell receptor (beta-TCR) gene occur in some patients with B cell chronic lymphocytic leukemia, we studied the arrangement of this gene in fourteen patients with multiple myeloma, a malignancy of the most terminally differentiated B cells. The gene was in germline configuration in peripheral blood lymphocytes (PBLs) and bone marrow samples of thirteen patients. By contrast, it was clonally rearranged in the marrow but not in the PBLs of one patient with stage IIA IgA-lambda myeloma. This patient's bone marrow consisted of 95% morphologically identifiable plasma cells which were CALLA-, OKT10+ (93%), and PCA-1+ (78%). Only 5% of marrow cells were small lymphocytes which contained T cell markers (CD3+ or CD2+). To eliminate the possibility that the small percentage of contaminating T cells contained the gene rearrangement, they were depleted by avidin-biotin immunoadsorption using the Leu4 determinant. Positively selected marrow T cells did not contain beta-TCR gene rearrangements. By contrast, the T cell depleted marrow contained the rearranged gene. This is the first demonstration that rearranged beta-TCR genes can occur in multiple myeloma.