Studies on immunomodulatory properties of isoniazid. I. Effect of isoniazid on mitogen- and anti-CD3 antibody-induced proliferation of human peripheral blood mononuclear cells and T cells.

Isoniazid, a tuberculostatic agent, induced in some patients lupus-like syndrome. Pathomechanism of this autoimmune phenomenon is unknown, and it is suggested that is associated with disturbances in immunoregulatory processes. Human peripheral blood mononuclear cells or T cells were isolated from healthy donors and were stimulated with phytohemagglutinin or antibody against CD3 cell receptor antigen. Proliferation, measured as thymidine uptake, was determined in in vitro cultures of the cells. Isoniazid added to cell cultures decreased proliferation at higher doses, and produced a slight increase in proliferation in concentration 10(-5)-10(-6) M. Isoniazid alone has no mitogenic activity. The viability of the cells, determined as the Trypan blue exclusion test, was decreased only at the presence of the highest used dose of isoniazid (10(-2) M), thus the results were not influenced by the toxic effects of the drug.