| BackgroundSome studies have shown that the level of anti-dominant antigens Ig G antibody, dominant antigens being associated with invasive infection, has increased in patients with invasive candidiasis(IC). Ig G antibody may be suitable to be used as a diagnostic index of IC. And our previous work also has found that anti-dominant antigens(such as Enolase, etc.) Ig G antibody, dominant antigens being associated with invasive infection, can be detected early in the serum of more than 80% of IC patients. Before obtaining the positive results of Candida culture, the level of Eno-Ig G antibody has rapidly increased in more than 50% of these patients. Candida albicans are the common opportunistic pathogens, which often parasitized or colonized in humans. All kinds of Candida antigens have many opportunities to stimulate the immune system to produce immune response.Therefore, it is presumed that the rapid elevation of Ig G antibody levels in the early stage of infection may result from Candida colonization associated with humoral immune anamnestic response of dominant antigen, but there is no evidence.ObjectiveThis study was aimed to study the mechanism of the rapid increase of Ig G antibody level in the early stage of invasive infection after Candida colonization or parasitic, which may be due to the rapid proliferation of the humoral immune memory cells. In order to further verify the prediction results, the level of threekinds of antibodies in the patients with invasive candidiasis were determined.MethodsFirst, the oral Candida colonization mouse model was established, and then the mice were infected with Candida by intraperitoneal injection. We detected the number of Candida Enolase(Eno)-specific memory B-cells(Bm) in the spleen and the levels of Ig G, Ig M and Ig A antibody in the peripheral blood of immunocompetent and immunocompromised invasive candidiasis mice, and compared with the corresponding indicators of invasive infected mice without Candida colonization. ELISA method was used to detect the levels of Eno-Ig G,Ig M, and Ig A antibody in sera of IC patients.Results(1) The ELISPOT method for detecting Eno antigen-specific Bm was successfully established and optimized. The results showed that the optimal cell numbers of positive control wells and Eno specific antigen wells were respectively 10,000 cells/well and 500,000 cells/well and the optimum concentration of biotinylated Eno was 2 μg/m L.(2) After treatment of Candida colonization, the Eno antigen-specific Bm can be detected in the spleen lymphocytes of both immunocompetent and immunocompromised mice on the seventh day of invasive infection, and the counts of which were significantly more than that of mice without Candida colonization or with Candida colonization only.(3) The anti-Eno antibodies can be detected in the serum of Candidacolonized mice in the early stage of invasive infection, and most of them are Ig G antibodies.(4) Eno-Ig G antibody was positively correlated with antigen specific Bm(r=0.737,P < 0.01).(5) According to the results of the ELISA method for the detection of three types of antibody in serum of IC patients, the positive rate of Eno-Ig G antibody was significantly higher than that of Eno-Ig A antibody and Eno-Ig M antibody(χ2=29.851;P < 0.01;χ2=21.744;P < 0.01)Conclusions1. It was confirmed that the cause of the rapid improvement of Eno-Ig G antibody levels in the early stage of invasive infection after Candida colonization may be due to the rapid proliferation of the humoral immune memory cells.2. There was no significant increase in Eno-Ig G antibody level in mice with Candida colonization only.3. Anti-Eno antibodies were detected in the serum of IC patients in the early stage of invasive infection, and most of them were Ig G antibodies.4. Eno-Ig G antibody can be used for serological diagnosis of invasive candidiasis, and Eno is a dominant antigen.. |
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