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Poppers: Large Cancer Increase and Immune Suppression in Animal Tests
By John S. James
The amount of inhalant used--900 parts per million for 45 minutes a day--was selected to approximate social use of the drug.
Other laboratory tests found that isobutyl nitrite did not increase growth of the tumor cells; instead it suppressed certain immune functions, including cytotoxic T lymphocyte (CTL) activity, and the killing of tumor cells by macrophages--which was reduced 86% by 5 days exposure to the inhalation.
Previously published work by the same team(2) found that immunity in the mice recovered within 14 days of stopping the inhalant. (The current paper suggested that permanent damage might still be done if immune suppression allowed cancer, KS, or HIV itself, to become established.)
This
is the first study showing directly that nitrite inhalant can promote tumor
growth. Previously, epidemiological studies had found that use of poppers is
associated with KS, and also is an independent risk factor for infection with
HIV (suggesting that poppers may increase the risk that exposure to HIV will
lead to infection).
KS is believed to be
caused by a different virus, HHV-8, that presents little risk unless the immune
system is suppressed by other factors. (The tumor cells used in this research
were not KS, but they were a well-known cell line used in animal tests to
measure immune suppression.)
Comment
Malignancies are a major and increasing problem in AIDS, and it will be important to find out if use of poppers is contributing to their higher incidence.
One way to research this question would be to ask whether or not patients with lymphoma or other malignancies are more likely than others to have used these drugs.
References
1. Soderberg LSF. Increased tumor growth in mice exposed to inhaled isobutyl nitrite. TOXICOLOGY LETTERS, 1999; volume 104, pages 35-41.
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Los
Martes de Enkidu
A new study found that mice injected with cancer cells were more than three
times as likely to develop tumors if they inhaled isobutyl
nitrite--"poppers"--and that when tumors did develop, they grew four
times as rapidly in the inhalant- treated animals.(1) 75% of the mice receiving
nitrite developed the tumors in this test, vs. 21% of the control mice (which
received the same cancer cells but breathed only air instead).
