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The aim of the study was to examine the influence of free radicals: nitric oxide (NO), hydrogen peroxide (H202) and superoxide anion (O2-) on Trichinella spiralis infection in mice. The studies were performed on two strains of mice: C57BL/6 and BALB/c, which differ in immunological response to T. spiralis infection. Also the influence of AG--inhibitor of inducible nitric oxide synthase (iNOS) administered in the first days after T. spiralis infection (1-5 dpi) on the cytotoxic immune response and on the number of adult parasites as well as the influence of AG administered at the beginning of muscle phase of the T. spiralis infection (16-29 dpi) on the cytotoxic immune response and the number of muscle larvae was studied. Activation of macrophages can cause pathology. Contact of macrophages with antigens stimulates these cells to produce, among others, highly reactive inorganic compounds. There are free radicals: NO, H2O2 and O2-. NO, O2-, and their metabolites are highly toxic for most pathogens, including parasites. However, little is known about their role in the defense against T. spiralis infection. The performed studies have proved, that free radicals play role in the host immune response during both intestinal and muscle phase of T. spiralis infection in mice. In the intestinal phase of the T. spiralis infection cytotoxic immune response is activated in mice peritoneal cavity and in the muscle phase, the local immune response activated in the neighborhood of larvae in muscles appeared as the higher level of free radicals in blood and urine. Administration of AG between 1-5 dpi causes opposite reactions in two different strains of mice. In BALB/c mice AG causes fast expulsion of adult T. spiralis from the intestine but in C57BL/6 mice the expulsion of parasites is slower after AG. However, there are no differences between two strains of mice after treatment with AG between 16 and 29 dpi. AG causes diminution of larvae in muscles of both BALB/c and C57BL/6 mice. Inflammatory response in peritoneal cavity is observed later during the infection in "low responders" (C57BL/6) mice in comparison with "high responders" (BALB/c) mice. Thl like mice (C57BL/6) react stronger to AG treatment than Th2 like mice (BALB/c). It occurs as changes and fluctuations in free radicals levels and the number of peritoneal cells after AG treatment in C57BL/6 mice. Weak or no reaction on AG injections in BALB/c mice is responsible for more stabile and more sufficient defense response of the host to T. spiralis infection.

The inflammatory infiltration cells penetrating through the larval capsule walls were observed. The observation were carried out in the masseter muscle of the mice infected with Trichinella spiralis larvae only (control) or infected and treated with PHA-P, TFX or dexamethason. The more numerous cells, than in the control, in the mice treated with PHA-P and TFX were seen. Opposite, the fever numerous cells inside the capsula walls in the mice that received dexamethason were found. The authors supposed that the phenomenon of inflammatory cells penetration through larval capsule play an important role in the defence mechanisms of the host.

Mice received 5 ng of ricin 24 hours after infection (experiment I) or 1 ng of ricin twice, 24 hours and 17 days of infection (experiment II). Animals were killed in 7, 14, 21, 28, 35, 42 and 60 days after infection. In the jejunum and masseter muscle sections, CD4+ and CD8+ lymphocytes, mast cells and eosinophils were studied. Heavy suppression of CD8+ lymphocytes, strong eosinophils and less pronounced mast cells stimulation was observed in the jejunum of mice received ricin (experiment I). Worm expulsion in intestine was faster than in the control (opposite results in experiment II). The composition of cells infiltration in the muscle was in both experiments similar to the control, however, fewer CD4+ lymphocytes were observed in larva capsule and there were fewer muscle larvae. Therefore CD8+ cells are believed to take part in restricting only the muscle stage of trichinellosis.

Studies were undertaken to evaluate by parasitological techniques the course of intestinal and muscular invasions in mice infected with Trichinella spiralis and treated with TFX-Thymomodulin (TFX-Th). Studies were conducted on 120 mice of BALB/c and SWISS strains, infected each with a mean invasive dose of 300 T. spiralis larvae. TFX-Th (Thymoorgan GmbH Pharmazie Co. KG, Vienenburg, Germany) was administered subcutaneously at 30 mg/kg body weight. Depending upon duration of TFX-Th administration and stages of intestinal and muscular invasions, three experiments were distinguished in the study. The results indicated that TFX-Th promoted eradication of larvae from muscles, whether administered at the early of the late stage of T. spiralis invasion.

At the first experiment 20 Swiss male mice were infected with 100 larvae and 20 mice with 500 larvae T. spiralis per mouse. Two days after infection (d.a.i.) mice orally received 1.5 mg Cd (water solution CdCl2) each. 40 mice were infected only T. spiralis as control. At the second experiment muscle larvae used were isolated from mice (from the first experiment) which received Cd. 20 mice were infected with 100 larvae and 20-with 500 larvae per mouse. Two d.a.i. mice received 1.5 mg Cd. Mice from both experiments were killed at 5, 10, 20 and 42 d.a.i. Total number of adult T. spiralis worms present in the small intestine and muscle larvae were recovered by conventional technique. Results of the first experiment: the number of adult worms and muscle larvae recovered from mice received Cd. were statistically significant lower as in control. Results of the second experiment: the mean number of adult worms in experimental group and in control were the same but the mean number of larvae per gram of mice muscle were significant higher as in control.