Accumulating data are showing that the humoral immune response against tumors could favor tumor progression. However, no B lymphocyte pathology has been reported in cancer. Using anti-IgM Ab we nonspecifically depleted B cells in tumor-bearing mice, a treatment that resulted in significant reduction of tumor burden. We analyzed the B lymphocyte phenotype of abdominal lymph nodes and peripheral blood from advanced colon cancer patients by flow cytometry, and compared the B cell phenotype with that found in samples from normal donors. In both lymph nodes and peripheral blood of cancer patients, abnormal populations of B lymphocytes appeared that express an increased CD21 and/or sTn antigens on their cell surface. All patients showed a reduction of CD19+ cells. In a limited clinical test, we analyzed the effects of a partial B cell depletion with Rituximab. The treated patients did not develop any side-effects; the CD21-hyperpositive lymphocytes were reduced, but the proportion of sTn-positive lymphocytes remained unaffected. Apparent reduction of the tumor burden was reported in 50% of the patients when the treatment was ended.

Clonal T cell populations with idiotype specificity are present to CD3 stimulation which boosts antitumour effector mechin the peripheral blood of a proportion of patients with multiple anisms. 15 It has also been shown that increased numbers of myeloma. We have identified the presence of both T cell subactivated suppressor T cells or NK cells are a good prognostic populations with a specificity for autologous immunoglobin factor at diagnosis. 16,17 fragments and T cell receptor ␤ gene rearrangements in periph-The presence of T cell receptor ␤ gene rearrangements has vations provide evidence for the existence of idiotype-reactive

Summary. The presence of T-cell clones in peripheral blood has been previously shown to be associated with a survival advantage in patients with multiple myeloma and suggests that the expanded T-cell populations may be involved in an anti-tumour response. We studied the T-cell receptor (TCR) repertoire of 38 patients with myeloma to identify and characterize the expanded T-cell populations by flow cytometry. T-cell expansions were found in 79% of the patients. The expansions occurred randomly among the 21 variable regions of the TCR b chain (Vb) studied, representing 62% of the V-b repertoire, and were stable during an 18-month follow-up. The phenotype of the expanded V-b populations was predominantly CD8 1 , CD57 1 , CD28 2 and perforin 1 , which differed significantly from the other nonexpanded Vb populations. The expression of the apoptosis markers Fas (CD95) and bcl-2 were similar between the expanded and non-expanded Vb populations. In conclusion, expanded T-cell populations were frequent in patients with myeloma, they remained unchanged during follow-up and had phenotypic characteristics of cytotoxic T cells. These data add further support to the concept that the T-cell expansions may have an immunoregulatory role in myeloma.

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Fetal DNA can be reliably detected in maternal plasma from early in pregnancy and normally is cleared within days of delivery.