Evaluation of the levels of circulating carbohydrate antigen and anti-SWAP antibodies in patients with active Schistosoma haematobium infection and its relation to morbidity changes

ABSTRACT

The immune responses of schistosomiasis and its relation to morbidity changes is important to understand the pathogenesis of this disease. The aim of this study is to evaluate the levels of circulating antigen and anti-SWAP antibodies and its relation to morbidity changes in patients with active Schistosoma haemtobium infection. An antigen enzyme-linked immunosorbent assay [ELISA] employing monoclonal [mAb] 128C3/ 3/21 was used to detect circulating parasite-derived antigen in the sera of 35 of actively infected schistosoma haematobium patients [31 males and 4 females, 5 to 25 years of age] seen in the out patient clinic of Assiut University Hospital. AntiSWAP [soluble adultworm antigen preparation] immunoglobulins IgG1. IgG4 and IgE were performed for 25 of them. Patients were treated with praziquantel [PZQ] and re-evaluated after 1, 3, and 6 months. Changes in morbidity were evaluated using ultrasonographic grading of urinary bladder lesions. It was found that all patients had significantly high levels of circulating antigens in their sera i. e. above the cut-off value. The antigen level fell significantly in the follow cup visits [p<0.001]. Although the mean antigen level was still significantly reduced [p<0.001] at 6 months visit, 16 patients had high mean antigen level and 9 had rising levels of antigenaemia, reflecting reinfection in 6 patients and persistence of infection in the others. On the other hand, all patients had positive ELISA reaction for IgG1 and IgG4, while 5 patients had negative reaction for IgE through the different visits before and after treatment. The decrease in the mean levels of IgG1 and IgG4 were statistically significant only after 6 months of treatment, but the mean levels of IgE showed significant drop at 3 and 6 months of treatment. A significant correlation was found between the circulating antigen and the anti SWAP IgE during the active infection, but no significant correlation was found between the antigen level and IgG1 and IgG4. There was a significant correlation between the level of circulating carbohydrate antigens and morbidity changes of the urinary bladder. On the other hand there was no significant correlation between the anti-SWAP antibodies and morbidity changes. We conclude that ELISA assay for detection of circulating carbohydrate antigen of S.haematobium is valuable and sensitive in diagnosis of active infection, measurement of intensity of infection and detection of reinfection as well as evaluation of the efficacy of treatment. Its level correlates with anti-SWAP IgE during active infection. In addition it correlates significantly with