NEMATOSPIROIDES DUBIUS : SUSCEPTIBILITY TO INFECTION AND THE DEVELOPMENT OF RESISTANCE IN HYPOTHYMIC (NUDE) BALB/c MICE

Summary BALB/c‐nu/nu mice and their intact nu/+ littermates are equally susceptible to infection with third‐stage larvae of Nematospiroides dubius . Unlike their heterozygous littermates. however, the nu/nu mice are unable to form granulomata in the intestinal wall and become only partially resistant to rechallenge. Following two or more infections, nu/nu mice maintain a high burden of adult intestinal worms, whereas worms are lost from immune nu/+ mice. Studies in T cell‐injected nu/nu mice suggest that a full complement of T cells is needed to develop maximum resistance against the infective third‐stage larvae and to expel adult worms. Measurement of serum immunoglobulin levels indicate that infected nu/+ mice have very high levels of IgG 1 whereas the levels of IgG 2a are reduced. In infected T cell‐injected nu/nu mice, IgG 1 levels increase with the number of T cells injected, whereas IgG 2a levels are variable but always higher than in infected nu/+ mice.