Cannabis Compounds Found to Trigger Unique Immune Cells Which Promote Cancer Growth

A double edged sword. Cannabis could be beneficial when suppressing the immune system is wanted, on the other side it could promote cancer growth.

ScienceDaily (Nov. 24, 2010) 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."


Senior Member
Sofa, UK
Only just came across this old and neglected thread. Thanks Diesel!

It's not news that cannabis suppresses the immune response, but two implications leap out to me in light of recent publications on XMRV.

First: a few people have mentioned in the past that they suspect cannabis may have lowered their immune barriers around the time of onset, and I'm keen on that theory that only [temporarily] immune-suppressed people are susceptible to the original XMRV (or whatever) infection; it fits my experience.

Second though, the thought that hadn't struck me before: this may be the reason why cannabis is the only effective form of pain relief for so many different conditions! If it's the immune response (to something unknown) that defines the mysterious pain symptoms, then suppressing that immune response would provide pain relief. It might also suppress XMRV replication as a result, as per the recent paper on NF-kB.

It's still going to be a double-edged sword though I think, because the immune response is a response to something (XMRV), which has been called "autoimmune" up until now, I suspect, simply because we couldn't see the thing that the immune system is responding to (gammaretroviruses). So suppress the response, you suppress the symptoms...but what then happens to the pathogen your immune system was responding to? All interesting knowledge, but it could be very tricky to work out quite what to do with it all...

free at last

Senior Member
Thanks for this information, Some may remember my rather frequent comments about how i belive i set myself up for the beggings of ME/CFS by years of habitual cannabis use, I called it for want of a better word a immune dysfuntion primer.Meaning i primed my immune system to allow immune dysfuntion to take hold in my life the first sign of which was flu like attacks, then long periods of good health then another flu type attack, and on and on.No body around me ever caught this flu. Which ive always thought was rather odd. Being xmrv positive for the years i was smoking this drug, and with the viral triggers, i belive led to a situation where my immune system just completely malfuntioned, with all numbers of infections and illnesses taking hold. I have even said that times that i have started smoking it again, led to more ME type symptoms much more frequently. Which as this research is showing, makes a lot of sense, Its hard to tell if its a under productive or over productive immuner dysfunction. Infact it could even be both, under productive as in a low quality immune response. but over productive in attacking very frequently. Some may not term this a overactive immune response, as infections might have been the catalyst making the immune system fight harder much more frequently. But i think you get the picture, by suppressing the immune system, xmrv and other germs could take hold much more readily. I know there are users who swear by its benefits, well i had benefits from it too. untill that is after about a weeks worth of using, then the symptoms would start and i had to stop. It defianatly produces more frequent symptoms for me now, hence ive stopped completly. Its been about a year at least since i dabbled. Be warned of long and lasting use. i also belive cannabis is not the only immune dysfuntion primer leading to immune problems, there could be many others, and ive mentioned before what these could be. Its anybodys guess. but different senarios would appear to lead to similar immune problems. in diffent people. in others its not the primer thats important. But that there is a primer.
THe studies that show immune suppression were not done properly as newer studies and articles indicate. Not to mention most of the studies that show immune suppression were done in vitro with THC levels that were a 1000 times higher than would normally be administered. The other studies from the 70s and 80s were involving cannabis smokers/users and smoking itself is an immune suppressing act.

I don't think that there is any evidence good/bad for cannabis as of yet and research is so limited because of the government.