Macrophage activation during experimental allergic orchitis in rainbow trout (Salmo gairdneri).

Macrophages isolated from fish undergoing an experimentally induced autoimmune response against the testis were found to have been activated using several morphological and functional criteria. They exhibited increases in cell spreading, phagocytosis, reduction of nitroblue tetrazolium and acid phosphatase activity. In addition they possessed larger and more numerous cytoplasmic organelles and peripheral processes compared with control cells. Culture of the autoimmunologically elicited cells for 1 or 2 days resulted in their return to a non-activated state.