The pig as an experimental animal in plastic surgery research for the study of skin flaps, myocutaneous flaps and fasciocutaneous flaps.

The pig serves as an excellent model of skin flap research. Many flap types are available and flap designs can be modified easily for specific experimental requirements. Swine are large enough to permit multiple flaps and the skin color allows subjective observations of tissue circulation.

Susceptibility to bacterial sepsis. Accurate measurement by the delayed-type hypersensitivity skin test score.

To test the hypothesis that any alteration in the delayed-type hypersensitivity (DTH) skin test response (not necessarily total anergy) reflects increased susceptibility to bacterial sepsis, male Sprague-Dawley rats presensitized to keyhole-limpet hemocyanin were subjected to a 30% full-thickness scald burn. Susceptibility to bacteria was assessed by the intradermal injection of Staphylococcus aureus 502A. The DTH response decreased following burn injury from 6.6 to 3.9 mm on days 2 and 8. Skin abscess size increased from 5.8 to 9.3 mm on day 2 and 8.9 mm on day 8. There was a significant inverse correlation between DTH skin test score and abscess size. Histologically there was no difference in the overall leukocyte accumulation in the abscess or the DTH reaction between the two groups, yet the overall size of the abscess was greater and the swelling of the dermis in the DTH response was less in the burned rats.

Effect of cyclosporine on host defence.

To discover whether cyclosporine administered daily in therapeutic equivalent doses for 3 consecutive weeks suppressed host defence, the authors measured the delayed-type hypersensitivity (DTH) skin response to keyhole-limpet hemocyanin (KLH) in rats. Twenty, male, Sprague-Dawley rats were sensitized to KLH and reactivity was confirmed 14 days later. Following sensitization, cyclosporine (20 mg/kg orally) was administered daily for 21 days to 10 rats. The other 10 (control group) received equivalent volumes of diluent (polysorbate 80 and ethanol). There was no difference in the DTH response between the cyclosporine and control groups for 5 weeks following treatment. Larger doses of cyclosporine (100 mg/kg) given intraperitoneally 30 minutes before and 6 hours after skin testing, suppressed the DTH response (7.2 mm to 2.4 mm) but resulted in a high mortality (eight of nine rats) at 48 hours. Delayed-type hypersensitivity was also suppressed in the control group but to a lesser extent and with no deaths (6.4 to 3.9 mm, p less than 0.05). Cyclosporine, in therapeutic equivalent doses, does not suppress the nonspecific immune component of host defence as reflected by the DTH skin response in previously sensitized animals. This may partially explain the lower frequency of septic morbidity and mortality in cyclosporine-treated transplant patients, compared with those receiving conventional therapy.