Role of IgE in the pathogenesis of milk allergy in infancy: reassessment by a new ELISA technique.

An ELISA technique using labelled antigen for the determination of cow's milk specific IgE in serum is described. The use of labelled antigen, rather than labelled antibody as in the RAST, permits avoidance of interference by antibodies other than IgE, such as IgG, at times responsible for a negative RAST. The results obtained with the 2 techniques in 43 infants with a positive cow's milk challenge showed a positive RAST in 28%, a positive ELISA in 35% and a positive RAST or ELISA in 42%. These findings suggest that the use of both ELISA and RAST permits in vitro diagnosis of cow's milk allergy in more patients than either test alone.