effect of captivity on the immune response of the killifish, Fundulus heteroclitus L

Fundulus heteroclitus maintained under laboratory for more than four weeks showed a significantly lower immunocytoadherence (rosette) response to thymus‐dependent antigens (SRBC and DNP‐BSA) than newly captured fish. There was no comparable effect on scale allograft rejection nor in the response to a thymus‐independent antigen (DNP‐Ficoll) as measured by the rosette response. This suggests that captivity has a differential effect on a sub‐population of lymphocytes analogous to the T‐helper cells of mammals.