Two weeks of daily CBD decreased immune cell counts in the spleens of healthy rats without affecting their ability to kill infected cells

CBD at 5 mg/kg/day for 14 days decreased splenic T cells and non-T/NK CD45RA+ lymphocytes but not NK cells. Natural killer cell cytotoxicity was unaffected in both blood and spleen. A CB2 receptor antagonist showed a significant interaction with CBD, suggesting partial CB2 involvement.

63 adult male Wistar rats received intraperitoneal CBD (2.5 or 5 mg/kg/day) or vehicle for 14 consecutive days. Splenic lymphocyte subsets counted by flow cytometry. NK cell cytotoxicity measured by Chromium-51 release assay in both blood and spleen. CB2 antagonist AM630 co-administered in some groups.

CBD is widely marketed as safe and anti-inflammatory, but this study shows it can deplete specific immune cell populations in a major immune organ. This has implications for people taking CBD long-term, particularly those with compromised immune systems.

The selective depletion of T cells and B cells while sparing NK cells is an interesting pattern. It suggests CBD's immunomodulatory effects are cell-type specific, which could be therapeutically useful for autoimmune conditions but concerning for long-term immunosuppression.

Male rats only. Intraperitoneal administration does not reflect typical human oral use. Healthy animals may respond differently than diseased ones. CBD doses may not be equivalent to human doses. Fourteen-day exposure is relatively short.