Age-related suppression of murine lymphoid cell blastogenesis by marijuana components

Marijuana components modulate a variety of immune response parameters. The cannabinoids delta 9-tetrahydrocannabinol (THC) and 11-hydroxy-tetrahydrocannabinol (11 OH-THC) are known to depress the in vitro proliferative response of murine lymphoid cells to the mitogens concanavalin A (Con A) and phytohemagglutinin (PHA). In the present report the effects of THC and 11 OH-THC on adult thymus and spleen cells were compared to effects on lymphoid cells of those organs from juvenile mice at various ages. The results demonstrate differences in susceptibility to cannabinoid-induced suppression by lymphoid cells from different organs and different age mice. In adults, thymus cells were suppressed more readily than spleen cells. Splenocytes from mice under 2 weeks old were suppressed much more readily than those from older mice. Cell populations from organs with higher proportions of L3T4+/Lyt2- cells were more difficult to suppress. The possible mechanisms involved and directions for future work are discussed.