New study reveals how cannabis suppresses immune functions

An international team of immunologists studying the effects of cannabis have discovered how smoking marijuana can trigger a suppression of the body’s immune functions. The research, published in the European Journal of Immunology, reveals why cannabis users are more susceptible to certain types of cancers and infections.

The team, led by Dr Prakash Nagarkatti from the University of South Carolina, focused their research on cannabinoids, a group of compounds found inside the cannabis plant, including THC (delta-9 tetahydrocannabinol) which is already used for medical purposes such as pain relief.

“Cannabis is one of the most widely used drugs of abuse worldwide and it is already believed to suppress immune functions making the user more susceptible to infections and some types of cancer,” said Dr Nagarkatti. “We believe the key to this suppression is a unique type of immune cell, which has only recently been identified by immunologists, called myeloid-derived suppressor cells, MDSCs.”

While most immune cells fight against infections and cancers to protect the host, MDSCs actively suppress the immune system. The presence of these cells is known to increase in cancer patients and it is believed that MDSCs may suppress the immune system against cancer therapy, actually promoting cancer growth.

Dr Nagarkatti’s team demonstrated that cannabinoids can trigger a massive number of MDSCs through activation of cannabinoid receptors. This research reveals, for the first time, that marijuana cannabinoids may suppress the immune system by activating these unique cells.

“These results raise interesting questions on whether increased susceptibility to certain types of cancers or infections caused from smoking marijuana results from induction of MDSCs,” said Nagarkatti. “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.”

In a related study, also published in the European journal of Immunology, Dr Christian Vosshenrich from the Institut Pasteur in Paris, reveals that when cancer cells grow they produce a molecule called interleukin-1 β (IL-1β), which also triggers MDSCs. This study identifies how MDSCs produced during cancer growth also weaken the ability of immune cells to kill cancer cells.

“Marijuana cannabinoids present us with a double edged sword,” concluded Dr Nagarkatti. “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.”


2 thoughts on “New study reveals how cannabis suppresses immune functions

  1. ~E

    This is… sort of a ridiculous conjecture… it’s NOT marijuana or cannabinoids that cause this reaction. These people in SC are not the first to have done this research – it’s awkward to see so many try to form poorly thought out conclusions based on things that have all been done before. This immunosuppressive response is NOT due to the marijuana. IT’S DUE TO *SMOKING* ANYTHING! The lungs incur all sorts of damage from particulates, gases, smokes and temperature extremes in our lifetimes, and ANY AND ALL OF THESE THINGS TRIGGER THE SUPPRESSION OF THE IMMUNE SYSTEM. Utilizing a vaporizor, or even better – ingesting cannabinoids through the use of Marinol or complete ingestion of the plant with food, will not show these same properties. A flawed study.

  2. D.M. Thraam

    Who funded this study? The trouble with USA based cannabis research is that it is funded by governmental organisations that pay researchers to go search for anything negative about marijuana. As the states grow closer to legalisation of a drug that is – like all drugs – never completely safe for every user but which is the least problematic by far, compared to all drugs people take to feel good, digging up dirt like this becomes more and more desperately done.

    Pharmaceutical companies, which in the age of corporatism have immense control over our lives and get too much money for less and less helpful or truly new medicines, really don’t want to see cannabis get legalized. It’s unpatentable.

    Immunosuppressive? That’s really reaching. There’s less cancer and heart disease amongst the people I meet in life who smoke (or consume by healthier means) marijuana than those who drink a beer or two every day instead.

    I am not insisting this study is faked – I just want to know if it was funded by the same institutions that have a proven track record of exaggerating or flat-out lying about this drug for the past half century or so. And what about those studies that suggest cannabis may break down tumors? Those never get funded in the USA, of course. I just want some truth, is this too much to ask?

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