Effects of salmeterol on host resistance to Trichinella spiralis in rats.

Salmeterol is a long-acting beta2-adrenoreceptor agonist. The compound has previously been screened for immunotoxic potential in a repeated dose toxicity study in rats for 28 days. The total serum IgG levels were increased at dose levels of 2 and 10 mg/kg/day. Presently, salmeterol was studied in an immune function assay addressing the host resistance to Trichinella spiralis parasites. Rats were daily treated with salmeterol for 28 days at dose levels of 0, 2, 6 and 10 mg/kg/day. On day 29, the animals were infected with T. spiralis parasites. After six weeks, host resistance was examined. The numbers of T. spiralis muscle larvae in the tongue nor the inflammatory reactions around the encapsulated larvae were affected by salmeterol treatment. The yield of muscle larvae in the whole carcass was not changed either. The IgM, IgA and IgE antibody responses to T. spiralis were unaffected. Only at the highest dose level tested, the anti-T. spiralis IgG antibody response was decreased significantly. However, salmeterol's interference with the generation of anti-T. spiralis antibodies of the IgG subclass apparently did not adversely affect the resistance to infection.