Injection of detergent-denatured ovalbumin primes murine class I-restricted cytotoxic T cells in vivo.
Complex adjuvant formulations have been used to introduce soluble protein antigens into the "endogenous" processing pathway and hence to elicit specific, major histocompatibility complex class I-restricted cytotoxic T lymphocyte (CTL) responses. We tested if simple modifications of a model protein antigen, i.e. ovalbumin (OVA), can render it immunogenic for murine class I-restricted CTL when injected into mice in soluble form. Injection of 1-100 micrograms native OVA into C57BL/6 (H-2b) mice did not stimulate a class I-restricted CTL response. In contrast, immunization of mice with 0.5 to 10 micrograms sodium dodecyl sulfate (SDS)- or deoxycholate (DOC)-denatured OVA efficiently primed CD8+ CTL specific for the well-characterized Kb-restricted OVA257-264 epitope. Gel-purified SDS-denatured OVA devoid of protein fragments and excess detergent efficiently stimulated a specific CTL response in vivo. OVA preparations denatured by heat or urea treatment were not immunogenic for murine CTL. Injection of non-treated or detergent-treated, antigenic OVA257-264 peptide into mice did not elicit a CTL response. Thus, denaturation of OVA by simple detergents such as SDS or DOC dramatically enhances its immunogenicity for class I-restricted CTL but not all modes of denaturation are equally effective.