Circulating monoclonal B lymphocytes in non-Hodgkin's lymphoma

Using a sensitive flow cytometric method ("kappa-lambda analysis"), we have found monoclonal B lymphocytes in the blood of 71 of 91 patients with non-Hodgkin's lymphoma. The presence of the B lymphocytes was independent of the histologic subclassification of the patient's disease. When we performed simultaneous analysis of the surface light-chain type in tumor tissue obtained by biopsy, the apparent light-chain type of the blood monoclonal cells corresponded with that of the tumor in 21 of 23 patients (P = 0.03). There was no correlation of the presence of these cells in the blood with morphologic evidence of bone-marrow involvement by lymphoma, but there was a strong correlation with clinical staging. Studies performed during prolonged clinical remission showed that whereas 16 of 25 patients with nodular non-Hodgkin's lymphoma had persistence of monoclonal lymphocytes, none of the 14 patients with diffuse histiocytic lymphoma in remission had these findings (P less than 0.005). Our analysis for B-cell clonal excess demonstrates the persistence of circulating monoclonal lymphocytes during complete remission in patients with forms of lymphoma that have a high probability of relapse, but we did not find these cells in patients in remission from categories of lymphoma in which prolonged remission is associated with cure. It is possible that the circulating monoclonal lymphocytes in patients with lymphoma are malignant cells, and their disappearance or persistence after remission may have prognostic importance.