Oval immunization with enterocoated microbeads induces antigen-specific cytolytic T-cell responses

A cytolytic T-lymphocyte (CTL) response has been generated to a protein ant igen via oral administration in an experimental murine system, This was ach ieved by the formulation of the test antigen ovalbumin (OVA) in a pH-sensit ive microsphere particle (microbead) with an acrylic-based coating to avoid its degradation by gastric enzymes. Comparative studies of orally administ ered enterocoated microbead-OVA particles, versus the more traditional. for mulation of OVA in adjuvant (DETOX-PC) given subcutaneously as immunogen, w ere conducted; both elicited comparable responses in the generation of anti gen-specific lymphoproliferative and CTL responses. CTL lines generated via oral administration of antigen were shown to be CD3(+), CD4(-), and CD8(+) , CTL lysis of OVA peptide-pulsed targets was shown to be inhibited by anti -CD8 antibody. Whereas oral administration of pH-sensitive enterocoated mic robeads containing proteins has previously been shown to elicit antibody an d lymphoproliferative T-cell responses to protein antigens, this is the fir st demonstration of the generation of an antigen-specific cytolytic T-cell response via oral administration of a protein immunogen formulated in such microbeads.