Effects of methotrexate on the parasitic development of the nematode Dictyocaulus viviparus (Metastrongylidae), and on the immune response of infected guinea-pigs

Abstract

Methotrexate inhibited the growth of D. viviparus by acting either on the moult from the third- to the fourth-stage larva or on the growth of fourth-stage larva itself. Despite these effects of the drug, the early developmental stages of the worms primed the immune mechanism of the host; the inductive phase of antibody production was completed in less than 5 days. An effective immune response, however, was blocked by the continued presence of methotrexate which resulted in delayed elimination of a superinfection and the absence of anaphylactic antibody in the serum. Immune elimination appeared to require a quantitative threshold of worm antigen and host antibody.This work was made possible by the generous supply of infective helminth material from Messrs Allen and Hanbury Ltd, Ware, Herts. I should also like to thank Dr J. H. Humphrey and Dr S. R. Smithers of N.I.M.R. for their helpful discussions.