A NEW METHOD, DISTRIBUTION-ANALYZING LATEX IMMUNOASSAY (DALIA), TO MEASURE SPECIFIC IMMUNOGLOBULIN-G AGAINST MITE AND WHEAT ALLERGEN IN HUMAN SERA

A distribution-analyzing latex immunoassay (DALIA), based on the agglu tination of latex particles coupled with mite or wheat allergen, was d eveloped to determine allergen-specific IgG in human sera. The immune complex between chemically coupled-allergen latex and specific IgG was agglutinated specifically and efficiently by employing an IgM-type mo noclonal second antibody with strong amplification activity. The exten t of agglutination was evaluated by determining the relative ratio of volumes (RV) of agglutinates to residual nonagglutinating particles wi th a particle counter. This method exhibited a high sensitivity (detec tion limit less-than-or-equal-to 5 munits/ml) in the determination of allergen-specific IgG, and no influence of inhibitory factors such as competitive antibodies (specific-IgA, -IgM) and nonspecific IgG (less- than-or-equal-to 320 mg/ml) was observed. The concentrations of specif ic IgG against mite allergen in the sera of 130 allergy patients with atopic dermatitis and 52 normal subjects were 22.3 +/- 12.3 and 16.5 /- 4.2 units/ml, respectively, and the concentrations of specific IgG against wheat allergen in the same two groups were 5.4 +/- 4.2 and 2.1 +/- 2.2 units/ml, respectively. The coefficients of variation of intr a- and interassay ranged from 3.4% to 11.2% in both cases. The present method is an excellent homogeneous immunoassay which may be used as a routine assay that can measure 50 samples per hour without prior trea tment.