Adherent cells suppress measles and herpes simplex I virus-induced blastogenesis of multiple sclerosis lymphocytes

Viral antigen-induced blastogenesis of lymphocytes from multiple sclerosis (MS) patients was investigated to determine if the responses were actively suppressed. We found that depletion of adherent cells increased measles and herpes simplex I virus antigen-induced transformation of MS lymphocytes. Addition of indomethacin to cultures of unfractionated MS lymphocytes also caused an increase in viral antigen-induced responses. These two facts, plus finding that the cell type mediating the immunosuppression did not rosette with 2-aminoethylisothiouronium bromide hydrobromide-treated sheep red blood cells, indicate that the suppressed T-cell responsiveness of MS patients is caused by macrophages rather than T-cells. These results have a major implication for the divergent published data on blastogenesis induced in MS patient lymphocytes by specific antigens, viral or otherwise. We feel the inconsistencies may simply have arisen from the different lymphocyte isolation and washing procedures used giving variable levels of macrophages and, hence, variable levels of immune suppression. This clearly suggests that induction of blastogenesis in MS patient lymphocytes by a wider array of infectious agent antigens and by various neural antigens should now be undertaken using adherent cell-depleted lymphocytes.