Poppers may aid tumour growth

Poppers, also known as butyl nitrite and amyl nitrite, may aid tumour growth

in mice, according to a report in Toxicology Letters last month. Dr Lee

Soderbergh of the University of Arkansas injected tumour cells into mice and

then exposed them either to isobutyl nitrite or to air for 45 minutes a day. The

mice exposed to isobutyl nitrite were much more likely to develop cancers than

the mice exposed to air (75% vs 21% of the control group) and much more likely

to exhibit reduced macrophage activity against tumour cells. Mice exposed to

isobutyl nitrite were also much more likely to exhibit reduced cytotoxic T

lymphocyte (CTL) activity. CTLs target and kill virus-infected cells, and it is

thought that some of the cancers associated with HIV, notably Kaposi's sarcoma,

are caused by virus infections.

However, previous human studies by Soderbergh's team failed to show any

effect on CTL activity in males exposed to isobutyl nitrite, although natural

killer cell activity was reduced.

Although several epidemiological studies of people who develop KS have

suggested that use of poppers increases the risk of developing KS, this link has

not appeared in every study. Most researchers are convinced that the most

important factor in the development of KS is human herpes virus 8 (HHV8)

infection. See Kaposi's sarcoma in the A-Z of illnesses on this site for a full

discussion of the causes of KS.

Reference:

Soderbergh LSF et al. Increased tumour growth in mice exposed to inhaled

isobutyl nitrite. Toxicology Letters 104: 35-41, 1999.