Enhanced IgE response to Candida albicans in postoperative invasive candidiasis

Background Invasive candidiasis is a life-threatening complication problem in postoperative and immunocompromized patients, e.g. those treated by intensive care. Candida is frequently cultured from the mucous membranes of hospital patients and fungal cultures offer httle diagnostic help. Other diagnostic methods, such as blood cultures, serology and diagnostic imaging techniques produce results too late and, if positive, low sensitivity. Objective To study the value of Candida-specific antibodies, especially those of IgE class, in diagnosing invasive Candida infection. Methods The immunoglobulins IgE, IgG and IgM responses to antigens of Candida albicans in the sera of 14 patients with culture, biopsy and/or autopsy proven postoperative invasive candidiasis and of 11 colonized and 19 non-colonized operated patients were studied by mannan radioallergosorbent test (RAST), mannan enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Results Detection of IgE antibodies to C. albicans polysaccharide (mannan) and protein antigens proved specific and sensitive in diagnostics of invasive candidiasis after major abdominal surgery. IgE rose early in the course of the infection and the method made a clear distinction between invasive infection and mucous colonization. Immunoblotting for protein antibodies was most sensitive while nitrocellulose-RAST for mannan antibodies was most specific. The combined use of immunoblotting and RAST increased the sensitivity and the specificity. Determinations of anti-Candida IgG and IgM antibodies had low sensitivity and specificity. Conclusion Critically ill patients with invasive candidiasis develop IgE antibodies to Candida antigens probably because of disturbed TH₁/TH₂ responses. Determination of specific IgE antibodies can be used as a diagnostic aid in the early stage of invasive Candida infection.