Immunomodulation of T and B cell functions in multiple myeloma patients treated with combined erythropoietin and α-interferon therapy

T and B lymphocyte functions were investigated in the course of a long-term trial of recombinant human erythropoietin in patients with progressing multiple myeloma. Peripheral mononuclear cell as well as T and B lymphocyte cultures were established at the 1st, 13th, and last week of the 24-week protocol from 16 treated and 15 untreated patients. Control cultures from healthy individuals were also obtained. A suppression of phytohemagglutinin-induced proliferation of T cells was noted in all 1st-week cultures, whereas a variable increase of3H-thymidine uptake was noted at the end of the trial in the cultures from erythropoietin-treated patients. A significant increase was observed, however, in cultures from 5 erythropoietin-treated patients who also received α-interferon when their cells were grown in the presence of the hormone. In contrast, the pokeweed mitogen-driven in vitro synthesis of immunoglobulins was not significantly influenced by the duration of erythropoietin treatment, nor by addition of the hormone. IgG secretion by Epstein-Barr virus-transformed B cells in cultures from 9 erythropoietin-treated and 6 untreated patients was enhanced in the presence of both recombinant human erythropoietin and α-interferon. These data suggest that synergy between the two cytokines may variably modulate certain immune functions in vitro. This effect might account for the increase of serum IgM levels noted in some patients who received α-interferon. © 1995 Springer-Verlag.