Development and validation of an ELISA for hemoglobin-A2: a novel method for beta-thalassemia screening in developing countries.

Hemoglobin-A2 (HbA2) measurement in human hemolysates has great significance, since its level can indicate beta-thalassemia carrier status in otherwise healthy individuals. An ELISA for HbA2 using antiserum monospecific to the delta chain of HbA2 and affinity purified antirabbit gamma globulins (ARGG) conjugated to horseradish peroxidase (HRP) have been developed. The monospecific antiserum used does not cross react with other hemoglobins. Hemolysates from volunteers are used for measurement of HbA2. In a limited trial for beta-thalassemia carrier screening (n = 350), the results obtained with the developed ELISA are comparable with those obtained with a micro-column chromatography method (r > or = 0.89). The developed ELISA is simple, accurate, precise, inexpensive, and several samples can be processed simultaneously with ease, making this system a suitable candidate for transforming into a user friendly kit.