USC RESEARCHER EXPANDS UNDERSTANDING OF MARIJUANA'S HEALTH IMPACT

Chemical compounds in marijuana can suppress the body's immune
functions - potentially speeding the growth of some cancers but
possibly helping in the fight against arthritis, multiple sclerosis or
allergies.

The good-news, bad-news findings were published in this month's
European Journal of Immunology, based on a study led by USC researcher
Prakash Nagarkatti. An immunologist who has been exploring the
potential of cannabis for eight years, Nagarkatti refers to the
findings as "a double-edged sword."

Nagarkatti's earlier studies dealt mostly with marijuana's potential
to treat leukemia. The latest report, at first glance, seems to
contradict his earlier findings. But Nagarkatti says the seeming
contradiction just emphasizes the complexities of both marijuana and
cancer.

"Cancer is not one illness. It is a very wide range of illnesses,"
said Nagarkatti, the Carolina Distinguished Professor in the
department of pathology, microbiology and immunology at the USC School
of Medicine. "And marijuana has over 400 different chemicals. It's
such a complex plant that we don't know the impact of all of those
chemicals."

The latest study on lab mice opens avenues for more research on the
subject. Nagarkatti hopes it'll lead to human clinical trials.

He also knows it will stir up the medicinal marijuana
debate.

"I'm getting a lot of e-mails from both sides already," he
said.

Many comments tacked onto early online reporting about the study blast
Nagarkatti as anti-medicinal marijuana. Those commenting don't realize
his earlier studies showed the promise of marijuana components, or
that this study indicated as much positive and negative.

The research focused on cannabinoids, compounds found in the marijuana
plant, and their impact on myeloid-derived suppressor cells. Research
shows those cells suppress the immune system. Nagarkatti, along with
co-authors Venkatesh Hegde and Mitzi Nagarkatti, found cannabinoids
trigger creation of huge amounts of myeloid-derived suppressor cells
in mice.

If the findings in mice are replicated in humans, doctors might
re-think the use of the one FDA-approved, marijuana-derived drug -
Marinol - to battle the nausea of chemotherapy and stimulate appetite
in HIV-AIDS patients.

While reducing nausea, marijuana's cannabinoids might also speed death
by suppressing the immune system critical to battling many forms of
cancer and infections. Of course, since HIV-AIDS also destroys the
immune system, the impact of marijuana on the system in those cases
might be minimal.

Conversely, cannabinoids might be a new tool for doctors to treat
arthritis and multiple sclerosis. In those auto-immune diseases, your
immune system goes into overdrive, destroying healthy cells. By
suppressing immune response, cannabinoids could lessen the severity of
those diseases. It also could help people battle allergies and fight
transplant rejection, Nagarkatti said.

While smoking medicinal marijuana has been legalized in some states,
the only FDA-approved application of cannabinoids in the U.S. is
Marinol. Nagarkatti is fascinated by the medical possibilities of
marijuana cannabinoids, but he doesn't recommend self-prescribing its
use.

"It's a complex mixture of chemicals that's not something to be played
with," Nagarkatti said.