STRONGYLOIDES-STERCORALIS HOST-ADAPTED 3RD-STAGE LARVAE ARE THE TARGET OF EOSINOPHIL-ASSOCIATED IMMUNE-MEDIATED KILLING IN MICE

Host-adapted, transformed, Strongyloides stercoralis third-stage larva e (L3(+)) were previously found to be antigenically different from fre e-living, infective, third-stage larvae (L3). These antigenic differen ces were reproduced by transformation of free-living larvae in tissue culture medium at 37 C over 24 hr. Transformed L3 of both derivations were given as challenge infections in diffusion chambers to naive mice and mice immunized with S. stercoralis L3. Within 12 hr, the challeng e infections were killed regardless of whether the L3(+) were generate d in vitro or in vivo. Eosinophils, previously found to be important i n the immune response to S. stercoralis larvae, were recruited in the L3(+) microenvironment within 12 hr of challenge infection in immune m ice, which supports the previously proposed mechanisms of S. stercoral is larval killing. Thus, S. stercoralis L3(+) appear to be targets of the immune response in mice instead of being involved in immune evasio n.