Cerebrospinal fluid antibodies detected by ELISA against a 33-kDa antigen from spherules of Coccidioides immitis in patients with coccidioidal meningitis

Antibodies against a 33-kDa antigen from Coccidioides immitis were detected by ELISA in patients' cerebrospinal fluid (CSF). Anti-33-kDa antibodies were detected at dilutions > 1:80 in only 1 (1.4%) of 73 patients without coccidioidal meningitis but in 74 (71.8%) of 103 with meningitis. Anti-33-kDa antibodies were detected in 53 (91.4%) of 58 patients whose anti- coccidioidal complement-fixing (CF) antibodies were detectable and in 21 (46.7%) of 45 patients whose CSF was negative by CF test (positive predictive value, 99%; negative predictive value, 71%; sensitivity, 72%; specificity, 99%). Anti-33-kDa antibodies, among which IgG1 was the dominant subclass, increased when infections worsened and decreased when patients' conditions improved. Antibody concentration appeared to be independent of most baseline findings, although only 1 of 5 patients coinfected with human immunodeficiency virus had initially detectable antibodies. Measurement of anti-33-kDa antibodies is a sensitive indicator of coccidioidal meningitis and of its clinical course.