Detection of serum antibodies in coccidioidomycosis by solid-phase radioimmunoassay

A radioimmunoassay (RIA) was developed to measure antibody in coccidioidomycosis with improved quantitation. Sera from 41 patients with active coccidioidomycosis had a mean +/- SD value of 0.6 +/- 0.49 mg/ml. Twelve healthy controls and 23 patients with noncoccidioidal diseases had a mean level of 0.06 +/- 0.12. Complement fixation (CF) and RIA titers were also compared with the clinical course in 19 patients with active coccidioidomycosis (seven had pulmonary disease; 12 had disseminated disease). The RIA was most useful in pulmonary cases. Pulmonary patients who experienced an improvement in symptoms more often experienced a drop in RIA titer (all of four patients) than CF titer (two of four). Similarly, pulmonary patients who demonstrated radiographic improvements experienced a drop in RIA titer (four of five) more often than a drop in CF titer (three of five). In patients with disseminated disease, there was agreement between the two assays and the clinical symptom score.