Selected parameters of innate and adaptive immunity in carp in the second breeding season

Abstract

The immune response in fish includes both cellular and humoral components. The aim of the study was to analyze the specific and adaptive immune response of carp using such parameters as the respiratory burst of blood phagocytes, lysosomal serum activity and the proliferative activity of lymphocytes induced by T-dependent mitogens PHA and Con A. Blood samples from 70 clinically healthy carp with body weights from 90 to 400 g were collected during a breeding season of 7 months, in March, April, May, June, July, September and October, The water temperatures in these months were, respectively, 4°C, 11°C, 16°C, 18°C, 22°C, 14°C, 8°C, and the fish were exposed to the stress being caught in March and October. The effect of low temperature and the stress factor (catching) on the leukocyte population was a reduction in the total number of white blood cells and lymphocytes and an increase in neutrophils. A negative relationship between the respiratory burst in neutrophils stimulated and water temperature was shown. The lowest values occurred at temperatures optimal for carp (18-22°C). Lysozyme activity in the samples increased from March to October and was the highest in autumn. The lowest proliferative activity of T lymphocytes was found in March, the highest in June and July. This study is the first to show the effect of suboptimal temperatures and the stress of being caught on defense mechanisms in 9 to16-month-old carp during the breeding season. The results suggest that these mechanisms are influenced by interaction between the endocrine and immune systems, in which the presumably elevated cortisol level has an immunomodulatory function.