Isotype switch and idiotype variation in hairy cell leukemia.

Hairy cell leukemia (HCL) cells are B lymphocytes expressing monoclonal surface bound immunoglobulins, B cell specific antigens, and activation markers. Based on immunophenotyping analysis, HCL cells have been reported to express simultaneously multiple Ig heavy chain isotypes. This is in contrast with the majority of other B cell malignancies. To analyse the tumor cell Ig in more detail, we have prepared somatic cell hybridomas from two patients with HCL.