Effect of various levels of T-2 toxin in the immune system of growing pigs.

Four groups of seven-week-old pigs weighing about 9 kg were fed for three weeks a prestarter that contained 0.5, 1.0, 2.0 or 3.0 mg/kg of highly purified T-2 toxin. The average daily intakes of toxin by the pigs were 0.38, 0.81, 1.24 and 1.43 mg, respectively. The experimental and control pigs were immunised with 5 ml aluminum hydroxide gel-absorbed purified horse globulin on the first and fourth days of the treatment period. Blood samples were withdrawn on days 7, 14 and 21 and used for the determination of the titre of anti-horse globulin antibody, for an in vitro lymphocyte proliferation test, using purified horse globulin, phytohaemagglutinin and concanavalin-A and for determinations of the immune complex, the cytotoxic reaction and the phagocytic activity and phagocytic index of circulating granulocytes. The samples taken on day 21 were also used to determine the erythrocyte count, the mean cell volume of the erythrocytes, the haematocrit, the blood haemoglobin concentration, the leucocyte count and the proportion of T lymphocytes. At the end of the experiment samples were taken from the thymus, spleen and mesenteric lymph nodes for histological examination. The diets that contained 2 and 3 mg T-2 toxin/kg caused a significant decrease in the red blood cell count, the mean corpuscular volume and the haemoglobin concentration. A significant decrease in the leucocyte count and the proportion of T lymphocytes was observed in all the treatment groups. There were also dose-dependent, significant decreases in antibody formation and in the blastogenic transformation of lymphocytes, and mild to moderate reactive processes were observed histologically in the lymphoid organs.

The value of immunodiagnostic tests in detecting tuberculosis in an infected red deer herd and in eradication of the disease by selection.

The sensitivity and specificity of intradermal tuberculin test (Tb test) were studied in an infected red deer (Cervus elaphus) herd (n = 109) in comparison to the results of other examinations including gross pathology, histopathology, Mycobacterium bovis culture, and the lymphocyte-stimulation test (LST). In our case, relative sensitivity was 79.5% and relative specificity was 45.7%. The predictive value in negative and positive cases was 80.0% and 44.9%, respectively. On the basis of the results obtained, eradication of tuberculosis by the selection procedure from a herd of newly captured and colonized deer was performed using the Tb test. For the purposes of eradication by selection all deer responding to B-PPD were considered positive.

T-cell deficiency in Suffolk lambs.

In a flock of Suffolk sheep respiratory diseases were regularly observed, while a flock of Booroola sheep kept under similar feeding and management conditions remained healthy. Experiments were conducted to compare the immunological and haematological parameters of Suffolk and Booroola sheep of different age groups. The percentage of T and B cells in the lymphocyte population and the capacity for blastogenesis induced by nonspecific mitogens were analyzed. Suffolk sucking lambs had significantly (P < 0.001) lower Concanavalin A (Con-A) induced blastogenesis and significantly lower T cell percentage at 6 months of age than Booroola lambs of the same age. B cell percentage and the rate of blastogenesis induced by Phaseolus vulgaris lectin (PHA) were lower in Suffolk lambs, though the differences were not significant. Sucking and growing Suffolk lambs had significantly (P < 0.01) lower red blood cell count and packed cell volume than Booroola lambs of the same age. Blood haemoglobin concentration was also lower in Suffolk lambs. No consistent differences were seen between the two breeds in total leucocyte count. T-cell deficiency and anaemia could be corrected by treatment with the immunomodulator levamisole (administered at a dose of 3 mg/kg body mass intramuscularly, twice with an interval of 10 days) and with vitamin B12 (1,000 micrograms/animal i.m.), respectively. On day 16 after the first treatment, the T-cell percentage, Con-A induced blastogenesis, red blood cell count, and packed cell volume of growing Suffolk lambs increased. T-cell deficiency and anaemia, either separately or together, may explain the lower resistance of Suffolk lambs to opportunistic pathogens. The relative contribution of genetic and environmental factors requires further studies.