Marijuana Effects On The Immune System Biology Essay


Marijuana (mostly spelled as marihuana), also known as Cannabis is a name used for any number of methods used to prepare the Cannabis plant to be used for medicinal purposes or as a psychoactive drug. Cannabis is the most commonly used illegal drug in the world. Marijuana is abused by people because of the effects it has on people and its addictive nature. Dried leaves of the cannabis sativa plant are rolled into a cigarette and sometimes mixed with tobacco by people who abuse the drug. Once an individual has inhaled smoke from marijuana, it goes through the lungs into the blood stream. This transports the chemical throughout the body into different body organs. A lot of research has been done by scientists to determine the actions of chemicals from marijuana in the brain and its role in the immune system.

The psychoactive chemical compound that is contained in the cannabis plant is known as tetrahydrocannabinol (THC). Cannabis however contains more than 400 chemical compounds each of which has distinct effects. It is for this reason that marijuana is used for medicinal purposes. Some of the chemical compounds found in marijuana are able to boost the immunity of both animals and human beings. The aim of writing this paper is to highlight the role of marijuana in medicine and to give insight on a number of researches done on the same.

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Out of all the medicinal herbs used in the world, Marijuana is the most debated upon. Clinical researchers and anecdotes have documented the importance of marijuana in treatment of diseases (McPartland and Pruitt 5). The diseases that marijuana has played a role in treating include pasthma, glaucoma, multiple sclerosis and migraine. Nausea, anorexia and AIDS are also allayed by marijuana. McPartland and Pruitt noted that, "marijuana is mostly used by people who are immunocompromised by AIDS or cancer chemotherapy" (7). The reason why the use of marijuana has sparked many debates is because uncontrolled use may alternatively lead to compromise of the body's immune system (McPartland and Pruitt 8). Activists against use of the drug for medicinal purposes argue that there is no need to use it if alternative medicine is available. The Food and Drug Administration (FDA), Drug Enforcement Agency (DEA) and National Institute of Drug Abuse (NIDA) have to work together in order to come up with a highly purified and tested form of marijuana that can effectively be used in medicine without raising health issues (McPartland and Pruitt 11).

There has been an explosive accumulation of knowledge concerning the nature and mechanism of the immune response, including host immunity and resistance to bacterial infection as well as to infection by viruses, fungi and parasites. It is now recognized that both inborn and acquired immune responses are involved in recognition and interaction with microorganisms. The immune system is a complex network of cells and cytokines with the primary function of preventing infection. As well-controlled and resilient as the immune system is, however, many reports document the negative effects on immunity of environmental factors, including drugs of abuse (Herman et al. 332). Herman noted that, "various studies during the last decades have shown that cannabinoids have marked effects on resistance to infectious diseases, both intracellular opportunistic bacteria and a wide variety of viruses" (334). Laboratory studies with rodents have shown that specific cannabinoids alter susceptibility to intracellular bacteria that causes syphilis, and the herpes simplex virus, and, although still controversial, they may contribute to the more rapid progression of HIV-infected individuals to clinical AIDS and to increased susceptibility to opportunistic microbial infection (Herman et al. 338). Detailed studies confirmed that THC treatment of mice infected with Legionella affects both innate and adaptive immunity.

The discovery of receptors that bind chemical compounds in the cannabis plant in 1990s helped scientists to understand the nature of marijuana derivatives (Massi et al. 3133). Cannabinoids have been shown to induce their biological effects mainly by binding to specific cannabinoid receptors (CB). As far as the current research is concerned, two main subtypes of cannabinoid receptors have been identified. These are the designated cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2). Massi noted that "although CB1 is predominantly expressed in the brain, it has also been detected in the periphery" (3134). Conversely, CB2 receptor subtype appears to be the dominat form of cannabinoid receptor within the immune system, with almost no traces in the brain, and its level is higher than that of CB1 in immune cells. CB2 receptors appear to be readily expressed by immune cells, while CB1 receptors are probably regulated in the immune system (Massi et al. 3137). CB2 receptors therefore play an active role in boosting the immunity of human beings and animals. The cannabinoids' role in immune system regulation, health and disease needs to be clarified not only in marijuana smokers but in non-users as well (Massi et al. 3139).

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The cannabinoid that has been linked to the majority of the immunosuppressive effects attributable to marijuana is delta-9-tetrahydrocannabinol (THC), its major psychoactive component. Studies using in vitro and in vivo experimental models have indicated that marijuana or THC affects cell immunity, humoral immunity, and cellular defenses against infectious agents (Guy 62). Guy also noted that "compromised resistance in mice, rats, and guinea pigs to infection with amebae, herpes simplex virus, Friend Leukemia virus, Listeria monocytogenes, Staphylococcus aureus, Treponema pallidum, and Legionella pneumophila has been reported" (63). Although there are numerous reports relating to the deleterious effects of THC, cannabinoid has been reported to have therapeutic potential. Major breakthrough has been made in the pharmacology and molecular biology of cannabinoids. High-affinity and low-affinity cannabinoid ligands, non-cannabinoid ligands, and receptor subtype-specific antagonists have been developed. Moreover, cannabinoid receptor subtype-specific molecular probes and antibodies as well as knockout animals have become available in the last few years (Guy 64). These experimental agents should prove highly useful to basic scientists and clinical researchers as they assess the acute as well as long-term effects of marijuana and cannabinoids on the immune system. The collective data got through the study of cell culture using different immune cell groups obtained from animals or humans, including those obtained from animal models of infection, are in line with the assertion that marijuana and cannabinoids affect the functionality of immune cells and can apply lethal effects on humans' resistance to infection (Guy 73).

The first logical contemporary study of chronic use of cannabis was the Indian Hemp Drugs Commission Report at the end of the 19th century. The British government decided not to forbid cultivation and commerce of cannabis after making sure that it had relatively small undesirable effects on health (Lindsay 65). Lindsay noted that "similar conclusions were obtained in the 'LaGuardia Report' of 1944, Mayor's committee on marihuana, which was the first to employ clinical and scientific methods of analysis" (65). There have been a number of reports on the affects of short term or chronic cannabis use in humans. It was reported that peripheral blood lymphocytes from chronic cannabis smokers showed significantly reduced responses to allogenic cells. This finding was confirmed by Lindsay who also after research discovered that the number of T-lymphocytes in the peripheral blood of marijuana smokers is markedly reduced. Scientists in the 20th century reported that the capacity of T cells from chronic marijuana users was reduced by 5%. Some of those results were disputed by other studies conducted. It was later reported that the CD4:CD8 ratio in blood was reduced in habitual marijuana users (Lindsay 69).

For years, cannabinoids have been considered, in vivo and in vitro, as immunosuppressive

agents. The possibility of a relationship between cannabinoids and immunity dates to the

1970s, when it was reported that marijuana smokers had more frequent recurrences of herpes simplex virus infection (Molina-Holgado et al 318). Currently, it is known that this immunomodulatory role is mainly emphasized via specific cannabinoid receptors expressed by both B and T cells. There are several immune targets for the effects of cannabinoids, including macrophages. Molina-Holgado discovered that "immunosuppression that is induced by taking marijuana may have implications for the treatment of neurological disorders associated with excess immunological activity" (319).


There are mixed results from scientific research done on the effect of the cannabis sativa herb as far as the body's immune system is concerned. Scientists have confirmed that continued intake of marijuana boosts the body's immune system to some level. Some chemical compounds from the cannabis sativa plant modulate resistance of the body against some bacteria as well as viruses.

There is a direct relation between the use of addictive drugs such as marijuana and the body's susceptibility against certain infectious diseases including AIDS. Clinical and experimental animal studies, both in vivo and in vitro, indicate that the abuse of such drugs by individuals is associated with enhanced susceptibility to infectious diseases. One mechanism by which these drugs of abuse affect immunity indirectly is stimulation of the HPA, resulting in glucocorticoid production and dysregulation of the immune system. Direct effects on immune cells involve ligation of specific receptors that affect immune responses in both animals and humans so as to alter susceptibility to infection. The involvement of specific receptors has been studied in detail for many years, first with opiates and more recently with cannabinoids and nicotine.

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The research conducted by most scientists does not however try to outweigh the balance between benefits and side effects of marijuana. It might be that the worst effects of the drug is greater than its medicinal benefits, the reverse may also be true. It is therefore imperative that scientists research further on all possible consequences of using the drug before it is implemented as a treatment method.