Cannabis Might Lower Immune Function, Raise Cancer Risk
Researchers from the University of South Carolina say cannabis users may be more prone to infections and cancer from suppression of immune function. The study authors say cannabinoids including THC in marijuana triggers the production of high numbers of myeloid-derived suppressor cells, MDSCs that have just recently been identified by immunologists and found in high levels in cancer patients.
Unlike other immune fighting cells, MDSCs suppress immunity. Dr Prakash Nagarkatti from the University of South Carolina studied compounds in marijuana that are currently used for medicinal purposes and found in the plant.
Immune Suppressing Action of Cannabis Could Prove Beneficial
Though the researchers found cannabis can stimulate large numbers of MDSCs, Dr. Nagarkatti says there may be instances when suppressing immunity could be helpful. He says, "Marijuana cannabinoids present us with a double edged sword. On one hand, due to their immunosuppressive nature, they can cause increased susceptibility to cancer and infections. However, further research of these compounds could provide opportunities to treat a large number of clinical disorders where suppressing the immune response is actually beneficial."
He notes the study raises questions about whether MDSCs actually increase susceptibility to cancer and infection. The presence of the immune suppressing MDSCs is known to increase in cancer patients, increase the chances of infection and promote cancer growth.
In a related study published in the European journal of Immunology, Dr Christian Vosshenrich from the Institut Pasteur in Paris, found that cancer cells also produce interleukin-1 β (IL-1β) that also triggers MDSCs and weaken immunity.
Dr. Narkattie says, "MDSCs seem to be unique and important cells that may be triggered by inappropriate production of certain growth factors by cancer cells or other chemical agents such as cannabinoids, which lead to a suppression of the immune system's response." The findings suggest cannabis users could be more vulnerable to cancer and infection, based on the findings that marijuana compounds stimulate production of the immune suppressing cells.