Alternatives to the standardized laboratory branch complement fixation test for detection of antibodies to Coccidioides immitis

Abstract

Antibody titers to Coccidioides immitis, using coccidioidin antigen, were determined by three methods: the standardized Laboratory Branch complement fixation method (LBCF), a modified version of the Viral and Rickettsial Disease Laboratory complement fixation test (VRDL-CF), and a quantitative immunodiffusion test (QID). Of the 133 samples evaluated, 72 were negative by each method and 57 (42 serum samples, 15 cerebrospinal fluid samples) were positive by all three methods. Four additional specimens (1 serum sample, 3 cerebrospinal fluid samples) were positive by QID alone. All positive patients were diagnosed clinically as having pulmonary or extrapulmonary coccidioidomycosis or both. When titers from two methods were compared, the agreement within ±1 dilution was VRDL-CF/QID, 88.5%; VRDL-CF/LBCF, 85.2%; and LBCF/QID, 82.0%. The agreement of these methods within ±2 dilutions was VRDL-CF/QID, 98.4%; VRDL-CF/LBCF, 96.7%; and LBCF/QID, 93.4%. The VRDL-CF and QID methods are simpler to perform; however, they are yet unrecognized as suitable alternatives to the more cumbersome LBCF. Our data show that they should be considered as options for C. immitis serology.

Isolation of Coccidioides immitis F antigen by immunoaffinity chromatography with monospecific antiserum

“…The IDCF assay is a highly specific procedure for establishing the diagnosis of coccidioidomycosis (8)(9)(10)14). Although the results of this assay correlate with those obtained in the CF test (7,10,11,20), it is not known whether the two procedures detect the same or different antigens. We have not yet evaluated the reactivity of the purified F antigen in CF assays.…”

“…This procedure is designated the IDCF assay, and the precipitinogen is referred to as the F antigen (10). It has not yet been proved that the F antigen is identical to the CDN component which reacts with antibody in the CF assay; however, the strong correlation between the results of the two assays (7,10,11,20) and the finding that both the F and CF antigens are labile to heating at 56°C for 30 min (10, 17) support this presunmption.…”

Serology of coccidioidomycosis.

“…The QID test for IDCF antibody is carried out by diffusing various dilutions of serum against a fixed concentration of antigen previously determined to have appropriate reactivity. Several workers have studied the QID (48,62,71,151,153). By refilling the antigen and serum wells 24 and 48 h after the original filling and taking a final reading at 72 h, Wieden et al (151) found that agreement between QID and CF titers (±+1 two-fold dilution) was 84.7%.…”

Comparison of immunodiffusion techniques with standard complement fixation assay for quantitation of coccidioidal antibodies

“…1977, F54, p. 127), 87% agreement within one twofold dilution between QID and CF tests was described. Recently, Wood et al (10) evaluated 133 sera or cerebrospinal fluid specimens of which 57 were positive by either the CF technique or the QID method, and four were positive only by the QID method. Overall agreement within one twofold dilution was 82% (50 of 61).…”

“…Both procedures are dependent on the consistent quality of antigen. The CF test, considered a reference method for 30 years, is faster but more complex and expensive (10). The modified QID method is simpler and cheaper to perform but requires 72 h for completion.…”