The Effects of Long-Term Administration of Recombinant Alpha-2 Interferon on Lymphocyte Subsets,Proliferation,and Suppressor Cell Function in Multiple Sclerosis

The immunological effects of long-term treatment with recombinant alpha-2 interferon (rIFN-α₂) were investigated in multiple sclerosis (MS) patients treated with 2 × 10⁶ units of IFN or a placebo three times per week for one year. A mild lymphopenia was observed in IFN patients who also showed a decrease in the absolute number of total T cells in the blood (OKT3 binding cells); however, the percentage of cells reacting with OKT3, OKT4, and OKT8 antibodies did not change significantly during the study. The percentage of cells reacting with the Leu-7 antibody, which recognizes NK cells, was unchanged. During MS exacerbations, placebo patients showed a tendency for decreased levels of OKT3 and OKT8 cells. In contrast, IFN patients did not demonstrate a decrease in either OKT3 or OKT8 cells during disease attacks. Concanavalin A (ConA)-induced suppressor cell activity was depressed in both IFN and placebo-treated patients during attacks. Lympho-proliferative responses to phytohemagglutinin, pokeweed mitogen, and ConA were unchanged. These studies demonstrate that long-term treatment with rIFN-α₂ induces a generalized T-cell lymphopenia, but at this dose does not significantly affect the profiles of T-cell subsets and suppressor cell function in MS patients.