The Health Effects of Cannabis and Cannabinoids The Current State of Evidence and Recommendations for Research (2017) / Chapter Skim
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8 Immunity
8 Immunity
Pages 199-216
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From page 199... ...
• There is limited evidence to suggest that regular exposure to cannabis smoke may have anti-inflammatory activity. • There is insufficient evidence to support or refute a statistical association between cannabis or cannabinoid use and adverse effects on immune status in individuals with HIV.
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From page 200... ...
Again, these examples emphasize the very limited and extremely narrow scope of assessments that have been conducted to examine the effects of cannabis on immune competence in humans to date. This chapter reviews the current evidence on the association between cannabis use and immune competence in healthy populations and in individuals with infectious disease.
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From page 201... ...
Therefore, the evaluation of immune competence requires a comprehensive assessment of a broad range of different cell types and their functions, which to date has not been conducted in cannabis users. Is There an Association Between Cannabis Use and Immune Competence in Individuals Without an Infectious Disease?
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From page 202... ...
CD4+ peripheral blood T cells from cannabis users showed a statistically significant decrease in proliferative response to mitogenic stimulation (phytohemagglutinin [PHA]
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. A longitudinal study followed study participants from birth to 38 years of age in order to investigate potential associations between cannabis use occurring between 18 and 38 years of age and physical health problems at 38 years of age, including systemic inflammation as measured by C-reactive protein levels (Meier et al., 2016)
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From page 204... ...
Reduced immune competence due to cannabis smoke or cannabinoid treatment would be especially relevant in cases when immunocompromised HIV patients used the cannabis to stimulate their appetite or cancer patients used it to relieve the nausea associated with cancer chemotherapeutic drugs. Very few studies have investigated the effects of cannabis smoke or cannabinoids on the susceptibility to, or clearance of, infectious agents or on progression of cancer in human subjects.
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. By contrast, study participants in neither of the cannabinoid study arms experienced statistically significantly greater changes in lymphoproliferative responses to various mitogenic stimuli than did study participants in the placebo arm.
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Discussion of Findings Collectively, the studies suggest that cannabis smoke and/or cannabinoids do not adversely affect the immune status of HIV patients. However, each of the four studies possessed major shortcomings in experimental design which could have contributed to the absence of adverse effects being observed in HIV patients who used cannabis or cannabinoids; these shortcomings include study durations that where insufficient to
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From page 207... ...
. A subsequent prospective study investigated 690 patients infected with both HIV and HCV and who had no significant liver fibrosis or end-stage liver disease at baseline, of whom 40 percent smoked cannabis daily at study baseline (Brunet et al., 2013)
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Two studies suggested that cannabis use was not significantly associated with progression of liver disease or with fibrosis stage in HCV patients. Since chronic inflammation is a significant contributing factor to the progression of liver fibrosis, these findings appear to be consistent with the anti-inflammatory activity of cannabinoids observed in the immune competence literature reviewed above.
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From page 209... ...
The study included 272 HIV-infected study participants between the ages of 12 and 24 years, with a mean age of 21.5 years. In univariable analyses, no statistically significant association between lifetime cannabis use, as compared to nonuse, and oral HPV infection was identified (OR, 0.68, 95% CI = 0.36–1.30)
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From page 210... ...
Systematic Reviews The committee did not identify a good- or fair-quality systematic review that reported on the association between cannabis use and infection with Aspergillus. Primary Literature Infection with Aspergillus species can be life-threatening in immuno compromised patients, including those with prolonged neutropenia, hematopoietic stem cell transplant, solid organ transplant, inherited or acquired immunodeficiencies, diabetes, corticosteroid use, or diabetes (Cescon et al., 2008; Denning et al., 1991)
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. RESEARCH GAP Research is needed to determine whether chronic cannabis smoke or cannabinoid treatment alters immune competence in healthy or immuno compromised individuals as evidenced by an increased incidence of infectious diseases; an extended duration of time to resolution of infectious diseases; and altered progression of cancer through the modulation of immune competence.
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From page 212... ...
There is limited evidence of no statistical association between cannabis use and: • The progression of liver fibrosis or hepatic disease in individuals with viral hepatitis C (HCV) (daily cannabis use)
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From page 213... ...
Each of these limitations precludes drawing conclusions concerning the effects of cannabis on immune competence in humans with any reasonable level of certainty. REFERENCES Abo-Elnazar, S., M
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1996. Successfully treated invasive pulmonary aspergillosis associated with smoking marijuana in a renal transplant recipient.
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From page 215... ...
2001. Preventing opportunistic infections after hematopoietic stem cell transplantation: The Centers for Disease Control and Prevention, Infectious Diseases Society of America, and American Society for Blood and Marrow Transplantation practice guidelines and beyond.
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