• What are THC's main effects on the immune stystem?

    THC is primarily immunosuppressive, meaning that it reduces pathological immune responses. However, it might also help the immune system carry out jobs that it usually can't in certain contexts such as cancer.

  • Is THC anti-inflammatory?

    Yes, and anti-inflammation is one of the immunomodulatory effects of THC. This is another reason that THC is so versatile in the clinical setting, as many diseases have inflammation at their source and origin.

  • What are some immune disorders that THC can be used for?

    So far, the anti-inflammatory and immunosuppressive effects of THC have been found to be useful in cancer, Crohn's disease, fibromyalgia, Alzheimer's and even depression.

We’ve recently been bombarding you with a lot of information about the immunomodulatory effects of cannabis, and last week we focused on the immunomodulatory effects of CBD. This week we’re having a look at the immunomodulatory effects of THC to investigate its role in different immune-related diseases.

It’s important to remember that when it comes to cannabis research, it often happens that cannabis is studied as a whole plant, and not necessarily as separate cannabinoids. Much of the research that exists lumps all cannabinoids under the same umbrella. 

So to keep things interesting and to bring you new and exciting research that we haven’t already presented to you in other articles, we’re going to look at THC’s immunomodulatory effects in context. For all intents and purposes, THC contains many of the same immunomodulatory effects as CBD such as induction of apoptosis, antiproliferation, and an off switch for pathological immune responses. 

Instead of going into these in detail again, we’re going to look at the research that delves into THC’s role in different immunological diseases. Through that, we’ll investigate the different ways THC might work in the body to bring about those immunological responses. Let’s jump right in!

THC, cancer, and the immune system.

A digital anatomical artwork depicting a human head, hand, thoracic cavity, and heart.

Before we jump into the interest THC has created in its potential to treat cancer, let’s talk about why cancer is actually an immunological disease.

Cancer is essentially an immune disorder because it comes about when the immune system fails to do its job — attack and destroy unhealthy cells. Cancer cells are those that proliferate out of control, therefore causing tumours. On the other hand, autoimmune conditions ensue when the immune system fails to recognise the host cells and attacks healthy ones instead of sick ones.

How, then, might THC be useful in the treatment of cancer?

As cancer cells are those that proliferate out of control, and ones the immune system has failed to recognize, THC can intervene with tumor progression on a number of levels. The first is by inducing cell apoptosis - the programmed death of cancer cells that the immune system couldn’t take care of on its own. Interestingly, THC is thought to do this through autophagy — which literally means “self-eating”. In certain types of cancer cells, THC induces autophagy, therefore causing the cell to kill itself. It is a very important aspect of its anti-neoplastic properties. 

The second mechanism is via THC’s antiproliferative properties. THC may interfere with the tumor’s ability to grow by inhibiting pathways that lead to the growth of blood vessels. Cancers need blood to grow, and blood vessels grow in cancers. By inhibiting the growth of blood vessels, the cancers are essentially starved and can’t continue to grow. 

THC is also immunosuppressive.

A painting of a woman whose thoracic cavity is exposed, has wounds on her arms and legs, a concept of disease

In contrast, THC also has immunosuppressive qualities. This is actually true for most cannabinoids, and as we described in the article The Immunomodulatory Effects of Cannabis, it’s one of the most important properties of cannabis and cannabinoids as a whole.

But when we think about cancer, for example, this quality of immunosuppression is… counterintuitive. The immune system has already failed to recognize unhealthy, cancerous cells. Suppressing the immune system further, theoretically, can actually promote the growth of tumors. 

For example, in one study, researchers found that in murine models, THC actually increases breast tumor growth and metastasis. It does this by suppressing the immune system, therefore impairing its ability to actually interfere with tumour growth. 

By the same breath, THC can also improve immune-mediated cancer surveillance in certain contexts. It has become an extremely important part of THC-immunology research to identify in which context THC enhances the immune system and in which it suppresses it.

It may also be the case that THC acts directly on tumor cells to reduce cancer, but actually suppresses the immune system. This would mean that THC doesn’t use the immune system per-se to have anti-neoplastic effects.

The reason THC’s immunosuppressive qualities are important is because there are a lot of diseases caused by an overactive immune system. For example, Crohn’s disease and lupus are autoimmune diseases caused by overactive immune systems. It is another reason that THC is being investigated so thoroughly with respect to the immune system. 

Anti-inflammatory: a property that makes THC so versatile.

A photograph of a cannabis leaf on a rainbow background wall.

One of the properties that makes THC (and cannabis) so versatile is its apparent ability to reduce inflammation. It makes THC versatile because there are a lot of diseases for which inflammation is a primary factor.

For example, through being anti-inflammatory, THC might have positive effects on Crohn’s disease, fibromyalgia, Alzheimer’s and even depression. Typically, THC brings on anti-inflammatory responses by causing cell death of T-cells, a kind of immune cell that creates the inflammatory response. 

This is part of the immunomodulatory effect of THC. It’s also why many people use THC for inflammation. However, this is also why THC and other cannabinoids may not be a great therapy choice for those whose immune systems function properly. If immunosuppression is induced in a healthy immune system, then it may make a healthy person more susceptible to disease.

The immunomodulatory effects of THC are complex and it’s for this reason that there’s ongoing research to understand exactly in which context THC and other cannabinoids are useful in immunological diseases. As we demonstrated, the effects are multifaceted — on the one hand, THC might kill cancer cells and improve immune surveillance, but on the other hand, it’s one of the best immunosuppressive agents we have. 

The ongoing research into exactly how and when to properly use THC in the clinical setting is very much needed so that we can better extract the best clinical potential possible.

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