Quantitative inhibition elisa for diagnosis of schistosomiasis using human igg labeled with fluorescien and anti-fluorescein/peroxidase

Usually mouse monoclonal antibodies are used in inhibition assays for antibody determination. Interference may occur in these inhibition assays due to presence of naturally occurring anti-mouse antibodies in some human serum samples. To avoid such interference, human IgG isolated from a pool of serum samples of S. mansoni patients and highly positive for IgG against S. mansoni soluble egg antigen [SEA] was used in inhibition ELISA for diagnosis of S. Mansoni infection. The assay was based on inhibition of binding of human IgG labeled with fluorescein to S. mansoni SEA coating microtitration plates by tested serum samples. Plates were washed and labeled human IgG reacted with SEA was linked to peroxidase enzyme by incubation with anti- fluorescein/peroxidase conjugate. The assay showed 90% sensitivity and 96.3% specificity. The level of inhibition in ELISA showed highly significant positive correlation with stool egg output. To make the assay quantitative, serial dilutions of the highly positive human serum pool used for preparation of human IgG were applied in each plate and concentration of anti-SEA antibodies in serum samples tested was calculated from a 4-parameters logistic curve equation

Opportunistic intestinal protozoal infections in immunocompromised children

One hundred immunocompromised children and 100 house contact controls were chosen for this study. Patients included 52 nephrotic syndrome children receiving corticosteroids for more than one month [age 5.28 +/- 2.32 years], 14 protein-calorie malnutrition [PCM] patients [8 cases of marasmus aged 6 +/- 2.27 months and 6 cases of marasmic kwashiorkor aged 1.39 +/- 0.88 years] and 34 lymphomas patients [22 cases of Hodgkin's disease and 12 cases of non-Hodgkin's lymphoma aged 4.5 +/- 3.54 years]. Examination of concentrated stool was done using iodine stain of fresh mounts and modified Ziehl-Neelsen [cold acid-fast] to fixed smears. T-cell subsets were counted after staining with mouse monoclonal antibodies against CD4 and CD8 labeled with fluorescein. Both nephrotic syndrome and lymphomas groups showed affection of cellular immunity in the form of significant decrease in T-helper and H/S ratio and significant increase in suppressor T-cell subsets. Giardia lamblia, Entamoeba histolytica, Cryptosporidium parvum and Blastocystis hominis were the most frequent in patients group and were significantly more prevalent among patients than controls. No significant difference in the prevalence of Entamoeba coli and Chylomastix mesnili between the two groups was observed. C. Parvum infection was strictly confined to groups with T-cell subsets abnormalities [i.e. nephrotic syndrome and lymphomas groups]