Comparisons of mycelia- and spherule-derived antigens in cellular immune assays of Coccidioides immitis-infected guinea pigs

Abstract

The biological activities of four Coccidioides antigens were compared in skin test, macrophage migration inhibitory factor (MIF), and lymphocyte transformation (LT) assays of 137 Coccidioides-infected and 20 noninfected guinea pigs. Antigens included: C-ASWS-M, the alkali-soluble, water-soluble cell wall extract from mycelia of C. immitis; C-ASWS-S, the alkali-soluble, water-soluble cell wall extract from spherules; CDN-TS, a toluene-induced lysate of C. immitis mycelia; and spherulin, an autolysate obtained from spherules. CDN-TS proved significantly more reactive (P < 0.0001) in skin tests, eliciting a mean induration of 11.6 mm as compared with indurations of 6.6, 6.4, and 6.1 mm obtained with C-ASWS-S, spherulin, and C-ASWS-M, respectively. CDN-TS, C-ASWS-S, and spherulin were equally reactive in MIF assays and elicited migration inhibitions of 31.8, 30.8, and 30.7%. C-ASWS-M was significantly less reactive (P < 0.001), with a mean response of 23.5%. The highest level of activity in LT assays was obtained with C-ASWS-S with a mean response of 5,636 Δcpm as compared with responses of 3,624, 3,439, and 3,580 Δcpm with CDN-TS, spherulin, and C-ASWS-M, respectively (P < 0.01). All antigens were effective in distinguishing responses of infected versus noninfected guinea pigs.