Measurement of antibodies to Candida albicans as a screening test for humoral immunodeficiency.

In screening for defects in humoral immunity, as well as measuring serum immunoglobulins it is advisable to have some measure of antibody production, e.g., immunising with a test antigen and measuring the antibody response some days later. However, this delay may be inconvenient and requires a second blood sample. An alternative is to test for antibody to a widespread commensal organism to which the patient must have been repeatedly exposed. The measurement of antibody to E. coli by haemagglutination has been previously used for this purpose. We report here that an equally good and simpler alternative is to measure antibodies to the commensal Candida albicans by immunofluorescence. Using a polyvalent conjugate, all 114 blood donors tested had antibody titres greater than 8 to C. albicans; similar responses were noted in 20 children (aged 6 months-16 years) without recurrent infections. In contrast, anti-candida responses were low or absent as expected in patients with hypogammaglobulinaemia but also in some patients with other immunodeficiency diseases. Overall candida immunofluorescence closely paralleled E. coli haemagglutination.