Perturbations in the catfish immune responses by arsenic: organ and cell specific effects

The present study was an attempt to elucidate the effect of non-lethal arsenic (As) exposure (1/10 LC50) on different immunologically important organs and cells of a catfish. Clarias batrachus L. were exposed to arsenic trioxide for different time intervals, which resulted in significant, time-dependent changes in total head kidney and splenic leucocyte count (p<0.05) and reduction in the organosomatic indices (p<0.05) of these two important immunocompetent organs. Routine histological studies revealed arsenic induced changes in the cellular composition of head kidney and spleen. Arsenic also induced time-dependent and tissue-specific alterations in T and B cell functioning in catfish. When checked for its effects on macrophages, it was noted that arsenic interfered with bacterial phagocytosis. Furthermore, arsenic affected the general immune status of C. batrachus and rendered the fish immunocompromised and susceptible to pathogens.