IMMUNOMODULATION OF T-CELL AND B-CELL FUNCTIONS IN MULTIPLE-MYELOMA PATIENTS TREATED WITH COMBINED ERYTHROPOIETIN AND ALPHA-INTERFERON THERAPY

T and B lymphocyte functions were investigated in the course of a long -term trial of recombinant human erythropoietin in patients with progr essing 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. Co ntrol cultures from healthy individuals were also obtained. A suppress ion of phytohemagglutinin-induced proliferation of T cells was noted i n all Ist-week cultures, whereas a variable increase of H-3-thymidine uptake was noted at the end of the trial in the cultures from erythrop oietin-treated patients. A significant increase was observed, however, in cultures from 5 erythropoietin-treated patients who also received alpha-interferon when their cells were grown in the presence of the ho rmone. In contrast, the pokeweed mitogen-driven in vitro synthesis of immunoglobulins was not significantly influenced by the duration of er ythropoietin treatment, nor by addition of the hormone. IgG secretion by Epstein-Parr virus-transformed B cells in cultures from 9 erythropo ietin-treated and 6 untreated patients was enhanced in the presence of both recombinant human erythropoietin and alpha-interferon. These dat a 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 alpha -interferon.