Dose-Related Inhibition of Leukocyte Migration by Marihuana and Delta-9-Tetrahydrocannabinol (THC) in Vitro

¹ Department of Medicine, New York Medical College, New York, N.Y.; Renal Service, Department of Medicine, St. Joseph's Hospital and New Jersey College of Medicine and Dentistry, Paterson, N.J.

White blood cells from five chronic marihuana users (more than one exposure per week for more than one year) and five nonsmokers (no contact with marihuana) were examined after exposure to THC and marihuana extracts and THC and marihuana extracts preincubated with nonsmokers' serum.

The leukocyte migration inhibition test (LMI) revealed that all extracts inhibited migration, but did not kill the cells (Trypan Blue exclusion). The extracts affected white blood cells from smokers and nonsmokers alike, without demonstrating delayed hypersensitivity at levels of 0.01 to 2 µg per ml of THC.

Marihuana extracts caused effects at a concentration of about 2 µg of THC per ml which effects were significantly greater than those caused by THC extracts. This was interpreted to mean that substances other than THC are found in crude marihuana which also inhibit leukocyte migration. The inhibitory effect of these substances seems to be modified after incubating crude marihuana extracts with nonsmokers' serum. The effects of marihuana and THC on leukocyte migration were noted at 2 µg per ml, which is about 50 times the plasma levels in man after inhaling 10 mg THC.

Note:

The authors wish to thank Drs. Rhea Dornbush and Max Fink of the Department of Psychiatry, New York Medical College, for supplying the marihuana and -9-THC extracts, and Dr. Robert Goldstein of the Department of Medicine, New York Medical College for his continued interest and support.