Immunological unresponsiveness of neonatal rats to infection with Nippostrongylus brasiliensis. The competence of neonatal lymphoid cells in worm expulsion.

Mesenteric lymph node cells obtained from adult DA rats infected with caused expulsion of the parasite in syngeneic neonatal recipients. On the other hand, lymphocytes obtained from infected neonatal rats failed to cause expulsion of the parasite when transferred to adult syngeneic recipients. These studies show that neonatal lymphocytes are not competent to initiate worm expulsion and this may be due to impairment as a result of tolerance or to deficiency as a result of delayed ontogeny of the immune response. The implication of the finding is discussed in the context of current knowledge of the mechanism of worm expulsion.