The Effects of Cortisone Treatment on Natural Resistance and Acquired Responses of the White Rat to Infection with Litomosoides carinii

Abstract

The near absolute resistance of the mature white rat to infection with Litomosoides carinii has been confirmed. Although more than 90% of the infective larvae do not complete migration in this host and cannot be recovered, some of the larvae do persist long enough to elicit a serological response detectable by the in vitro test. Antibody was suppressed by preinfection treatment with cortisone acetate. Cortisone treatment also suppressed the natural resistance of the mature white rat to infection, but preinfection treatment with cortisone was not required to produce this effect. As a result of this change in susceptibility, worms were recovered in numbers approximating those recovered from the normal host, the cotton rat. A residual resistance, however, was manifested by the delay of worm migration to the pleural cavities and the stunting of growth and development of worms in cortisone-treated white rats.