Immunomodulative effects of some drugs of abuse on human peripheral blood lymphocytes

The cytotoxic effects of opiates, cocaine and their metabolites on peripheral blood mononuclear cells from healthy volunteers, concerning cell viability, were studied in a wide range of concentrations (ranging from 10-(2) to 10-(8) M), by 2 colorimetric in vitro assays, the neutral red uptake assay and thiazolyl blue tetrazolium bromide assay. All tested drugs of abuse and their metabolites were non-cytotoxic at concentrations lower than 10-(5) M. The possible immunomodulative effects of these substances were evaluated through phytohemagglutinin-induced lymphocyte proliferation ([3H]-thymidine DNA incorporation assay) as well as by a 51Cr release natural killer assay. The results showed immunomodulative effects of all the opiates tested. Cocaine, freebase cocaine and benzoylecgonine produced a statistically non-significant decrease of phytohemagglutinin proliferation. Cocaine induced a statistically non-significant increase, whereas freebase cocaine and benzoylecgonine showed a non-significant decrease of natural killer cell activity.