Effect of short term cocaine administration on the immune system of young and old C57BL/6 female mice

It has been shown that either cocaine or aging alone can alter the immune system. Our objective was to study if the immune system of aging mice was more susceptible to the effect of cocaine than the immune system of young mice. We used a short term (20 days) cocaine daily administration protocol. Cocaine only decreased the absolute number of Thy 1⁺, CD4⁺, CD8⁺, 1L-2R⁺, Mac 1⁺ and B cells, in the spleen of old mice. Old untreated mice had a lower number of Thy 1⁺ cells in the thymus, and a higher number of cells expressing IL-2R. Cocaine decreased the number of Thy 1⁺ cells in the thymus of both age groups. Old mice showed a lower number of IgA⁺ plasma cells in the intestinal lamina propria (ILP) than young mice. Short term cocaine administration provoked a decrease in the number of CD4⁺ cells in young mice 1LP and of CD8⁺ cells in old mice ILP. Our data suggest that cocaine can potentiate the effect of aging on the thymus and on the mucosal immune system. Taken together, our findings indicate that aging and cocaine can potentiate each other to impairing the host immune system.