Differential effects of marijuana components on proliferation of spleen, lymph node and thymus cells in vitro

Abstract

The effects of delta 9 THC and 11-OH THC on the proliferative response of murine spleen cells stimulated in vitro with the T cell mitogens Con A or PHA were compared with the effects of these drugs on the mitogen-induced proliferation of murine thymus and lymph node cells. Thymus cells were found to be suppressed at lower cannabinoid concentration than either spleen or lymph node cells. However, splenic cells were more easily suppressed than were the lymph node cells. Lymphoid cell numbers were varied from 1 × 10 6 to 8 × 10 6 cells and treated with a constant dose of either THC or 11-OH THC. When suppression was noted with spleen and lymph node cells, the smallest number of cells in the assay resulted in the greatest level of suppression of cell proliferation. No significant suppression to PHA induced proliferation was found for lymph node cells at any cell number tested. Thymus cells were always more readily suppressed than spleen or lymph node cells regardless of the number of cells in culture. Furthermore, 11-OH THC suppressed the responsiveness of the thymus cells to PHA more than to Con A under the experimental conditions used. Thus, the ability of cannabinoids to induce suppression of the proliferative response of lymphoid cells to mitogens depends on the organ source of the cells, nature of the cannabinoid (THC or 11-OH THC), dose of the cannabinoid, mitogen used (PHA or Con A), and number of cells in culture. These variables provide their own individual significance in terms of pointing to directions for further study as well as partially explaining the difficulties of comparing work from laboratory to laboratory where these variables are not necessarily constant.