Development of immuno sorbent agglutination assay [ISAGA] for determination of speeifie antihouse dust mite IGE

ABSTRACT

Atopy poses a world wide health problem to large segments of population and is relevant from early childhood to adulthood. Diagnosis of atopy is simply based on skin tests which must be avoided in many occasions, or on total Ig[E] estimation which may be misleading. Other tests to detect serum specific Ig[E] are expensive and need special instrumentation. This study presented a less expensive modification of ISAGA to detect specific Ig[E] antibodies of 180 asthmatic children and 89 healthy children control evaluated clinically and by pulmonary function. 137 children were proved to be asthmatic 59 [43.1%] of cases and 8 [8.9%] gave SPT and intradermal positive tests to house dust mite [HDM] allergen extract. Collection of the mite D-pteronyssinus from houses of all asthmatic cases and control detected high infestation rate in all houses [94.9 - 93.5% respectively]. Agglutination score [of three wells] encountered by different serial dilution among 59 atopic children with +ve SPT to HDM allergens showed that 1/25 serum dilution is effective to perform ISAGA test. Correlation of ISAGA with skin tests showed that the sensitivity of the test is 100% [67 positive by the test of 67 true positive] the test was [98.4%] specific [one false positive case out of 61 true negative]. The test also prooved to be reproducible. Application of the test showed that 76.1% of asthmatic patients had specific Ig[E], the test also correlates well with the intensity of the skin reaction. Such findings accomodate it as a test for atopy among asthmatics