You point to largely experiential evidence of the medicinal benefits of marijuana and the apparent absence of serious short-term toxicity. However, a note of caution is warranted. Although it is true that smoking marijuana carries no immediate risk of death, there may be serious adverse effects in the very patients for whom medicinal marijuana is most commonly considered (i.e., those whose immune defenses are already compromised by AIDS or cancer plus chemotherapy). For example, in patients with AIDS, marijuana use has been associated with the development of both fungal and bacterial pneumonias. [1,2] Moreover, among HIV-positive persons, marijuana use has been shown to be a risk factor for rapid progression from HIV infection to AIDS and the acquisition of opportunistic infections or Kaposi’s sarcoma, or both. [3]

Cellular studies and studies in animals lend support to these potential health consequences of marijuana. For example, delta-9-tetrahydrocannabinol has been shown to have immunosuppressive effects on macrophages, natural killer cells, and T cells, as well as on the response of mice to opportunistic infection. [4] In our own studies, [5] (and unpublished data) we recovered alveolar macrophages from the lungs of habitual marijuana smokers and found a significant reduction in their ability to kill fungi, bacteria, and tumor cells, as well as a deficiency in their ability to produce protective inflammatory cytokines, such as tumor necrosis factor (alpha).

Donald P. Tashkin, M.D. Michael D. Roth, M.D. . Steven M. Dubinett, M.D. .UCLA School of Medicine; Los Angeles, CA 90095-1690.

REFERENCES.

1. Denning DW, Follansbee SE, Scolaro M, Norris S, Edelstein H, Stevens DA. Pulmonary aspergillosis in the acquired immunodeficiency syndrome. N Engl J Med 1991;324:654-62. Bibliographic Links .

2. Caiaffa WT, Vlahov D, Graham NM, et al. Drug smoking, Pneumocystis carinii pneumonia, and immunosuppression increase risk of bacterial pneumonia in human immunodeficiency virus-seropositive injection drug users. Am J Respir Crit Care Med 1994;150:1493-8. Bibliographic Links .

3. Tindall B, Cooper DA, Donovan B, et al. The Sydney AIDS Project: development of acquired immunodeficiency syndrome in a group of HIV seropositive homosexual men. Aust N Z J Med 1988;18:8-15. Bibliographic Links .

4. Newton CA, Klein TW, Friedman H. Secondary immunity to Legionella pneumophilia. and Th1 activity are suppressed by delta-9-tetrahydrocannabinol. Inject Infect Immun 1994;62:4015-20. .

5. Sherman MP, Campbell LA, Gong H Jr, Roth MD, Tashkin DP. Antimicrobial and respiratory burst characteristics of pulmonary alveolar macrophages recovered from smokers of marijuana alone, smokers of tobacco alone, smokers of marijuana and tobacco, and nonsmokers. Am Rev Respir Dis 1991;144:1351-6. Bibliographic Links Accession Number: 00006024-199704170-00025