Hydatidosis: Preparation and evaluation of radiolabeled antigens and antibodies.

The present preliminary study intends to evaluate the in vitro use of hydatid antigen and their antibodies once labeled with iodine 125(I125) and characterized from viewpoint of radiochemical purity and immunoreactivity. Radiolabelled molecules gave satisfactory purity of 94% and 96%-98%, for hydatid antigen and IgG respectively. As regards, the specific activity of these latter, varied between 4.79 and 5.97 µCi/µg. The specificity test of radiolabelled IgG against the hydatid membranes showed a significant recognition that increased proportionally according to the contact surface. Likewise this immunoreactivity test performed with a simple binding assay, using human hydatid fluid antigen (HHF-Ag), previously fixed on a solid phase, gave satisfactory fixation rate of the order of 356 ±â€¯48.08cpm, 2539 ±â€¯550.12cpm and 6558 ±â€¯712.76cpm for the concentrations of 0.1 µg/ml, 2 µg/ml and 25 µg/ml respectively. Statistical study of 88 sera, carried out with radiolabelled antigen (125I-HHF-Ag) in competitive radioimmunoassay test (CRIA) showed highly significant difference (p < 0.0001) in the binding capacity of antigens from patients sera with hydatid disease (65.63 ±â€¯9.12) compared to the negative sera (19.25 ±â€¯14.84). No cross reaction was observed using sera from patients with toxoplasmosis (33, 07 ±â€¯13, 07) and the difference was highly significant (p < 0.0001) compared to E granulosus infected patient sera. Furthermore, this test seemed to be sensitive since among the 43 sera tested, only 37 (86%) were found to be positive by passive hemagglutination (HAP), while the totality (100%) responded positively by CRIA. Our findings are encouraging, suggesting that these radiolabeled molecules could be useful for advancing toward new diagnostic and therapeutic modalities.

In-house preparation and evaluation of (125)I-histamine progesterone tracer for radioimmunoassay of progesterone.

The progesterone tracer for the development of in-house radioimmunoassay was prepared in two steps clearly described. First, activation of 11α-hemisuccinate progesterone (progesterone-11 α HS) and labeling of histamine with (125)I, and second, conjugation of activated 11α-HS progesterone with iodinated histamine. The purification of the tracer was carried out by gel filtration on Sephadex G-25. The radiochemical purity of purified the tracer was 95%. The maximum binding using solid phase (coated tubes) reached 41% and the non specific binding didn't exceed 5%. The tracer stored at different temperatures 10°C and -6°C was stable during 12 weeks. The skim milk provided assay better sensitivity (0.22 ng/mL) than serum (0.28 ng/mL).