IDIOTYPE-REACTIVE T-CELL SUBSETS AND TUMOR LOAD IN MONOCLONAL GAMMOPATHIES

The presence of idiotype-reactive T-cell subsets and their relation to the tumor load were analyzed in 9 patients with monoclonal gammopathy of undetermined significance (MGUS), in 12 patients with multiple mye loma (MM) clinical stage I, and in 9 patients with MM stage II/III. An enzyme-linked immunospot assay was used to identify interferon-gamma (IFN-gamma)-, interleukin-2 (IL-2)-, or IL-4-secreting T cells after s timulation by F(ab')(2) fragments of monoclonal IgG. The response to a utologous IgG was significantly higher than that induced by isotypic m onoclonal IgG. Comparable results were obtained in a proliferation ass ay (H-3-thymidine incorporation). A total of 8 of 9 patients with MGUS , 7 of 12 patients with MM stage I, and 3 of 9 with MM stage II/III ha d T cells secreting IFN-gamma and/or IL-2 (T helper [Th1] type-1 cells ), whereas cells secreting both Th1 and Th2 or Th0 types of cytokines were more frequent in patients with MM, particularly in those with MM stage II/III. The number and frequency of Th1-type cells were signific antly higher in MGUS patients as compared with those of MM stage II/II I. The T-cell response was inhibited by an anti-DR antibody. The resul ts indicate that idiotype-reactive T cells of the Th1 and Th2 or Th0 s ubsets were present in MGs and might provide indirect evidence that id iotype-reactive Th1-type cells may have a regulatory impact on the hum an tumor B cells. (C) 1995 by The American Society of Hematology.