Inosiplex enhances the growth of Epstein-Barr nuclear antigen-positive B-cells from patients with rheumatoid arthritis and infectious mononucleosis.

The in vitro effects of inosiplex (INO) on proliferation of Epstein-Barr virus (EBV)-carrying B-cells were evaluated. As measured by 3H-thymidine uptake, INO significantly augmented the proliferation of long-term cultured Epstein-Barr nuclear antigen (EBNA)-positive B-cells which were obtained from patients with rheumatoid arthritis (RA) and infectious mononucleosis (IM). In co-culture experiments, INO and anti-immunoglobulin M antibodies coupled to sepharose (anti-mu) had additive effects on proliferation of EBNA-positive B-cells. We conclude that its direct effects on B-cell function should be considered when INO is used for the treatment of diseases characterized by B-cell hyperreactivity.