Generation of T cell clones binding F(ab')2 fragments of the idiotypic immunoglobulin in patients with monoclonal gammopathy.

Lymphocytes from two patients with multiple myeloma stage I and one patient with monoclonal gammopathy of undetermined significance were found to proliferate specifically in response to low concentrations of F(ab')2 fragments of the autologous M component. T cell clones isolated from repeatedly stimulated cultures bound specifically the autologous idiotype and proliferated after addition of soluble idiotype and exogenous interleukin-2. The majority of clones were CD8+ and showed negligible staining for CD4. Idiotype-binding clones could not be isolated from cultures of lymphocytes from a healthy control stimulated under the same conditions. The study provides support for the existence of idiotype-reactive T cells in monoclonal gammopathies. Such cells might have a regulatory role on the tumor cell clone and may be important for a future therapeutic approach.