Potentiation of T-lymphocyte function by bleomycin

Bleomycin, an anti-cancer drug, hitherto thought to have no effect on the immune response, was found to increase contact sensitivity in the guinea pig to 2,4-dinitrofluorobenzene. The drug was given in a single dose (125 mg/kg) on the day of or up to 3 days after sensitization, to achieve this effect. The drug was ineffective if given 3 days before or 4 days after sensitization. In addition, if given 2 or 3 days after sensitization, it caused increased T-cell proliferation in lymph nodes draining the skin sensitization site. It is suggested that the potentiating effect of bleomycin is not on suppressor cell function, as with cyclophosphamide, but might have an effect on local interleukin 2 production, particularly if given when T-cell proliferation is on the increase.