Adoptive Transfer of Immunity with Intraepithelial Lymphocytes in Cryptosporidium parvum-Infected Severe Combined Immunodeficient Mice

Intestinal infections with the protozoan parasite Cryptosporidium parvum are prevalent in both immunocompetent and immunocompromised hosts. Although C parvum is an important cause of outbreaks and opportunistic infections worldwide, little is known about protective mucosal immune responses. This is in part because animal models of infection are limited to those with genetic or induced immunodeficiencies.In this report, we isolated immune (primed) or nonimmune (unprimed) intraepithelial lymphocytes (IEL) from BALB/cJ mouse intestines, adoptively transferred them into C parvum-infected severe combined immunodeficient (SCID) mice, and evaluated infection and cell phenotype responses.Control SCID mice that received no IEL shed large numbers of oocysts throughout the experimental period (day 18 to day 72). Transfer of primed IEL significantly reduced fecal oocyst shedding in recipient SCID mice compared with SCID mice that received unprimed IEL or no IEL. SCID mice transferred with unprimed IEL shed variable numbers of fecal oocysts that increased and decreased in bursts until day 57 after infection. SCID mice transferred with primed IEL exhibited significantly higher proportions of T-cell receptor (TCR) alphabeta+, CD8+, and CD8alphabeta+ EL compared with inoculated SCID mice that received unprimed or no IEL.We conclude that primed IEL from immunocompetent mice may influence protective mucosal response against cryptosporidiosis when transferred into SCID mice. In addition, the increased percentage of TCR alphabeta+, CD8+, CD8alphabeta+ IEL in recipient SCID mice may reflect mucosal cell populations involved in these responses during chronic C parvum infection.