Primary interaction between antibody and components of Alternaria. II. Antibodies in sera from normal, allergic, and immunoglobulin-deficient children.

Antibodies in sera from normal, allergic, and immunoglobulin-deficient children were studied for binding to radiolabeled components of Alternaria tenuis. Significant binding levels were found in 103 of 105 sera from normal children. The levels were age-dependent, rising from a low point in the 7- to 12-month age group to adult levels by the age of 8 years. Levels of binding to two antigens, a culture filtrate derivative (125I-CLF) and a mycelial derivative (125-I-HS), were similar. Sera from asthmatic children with strong immediate skin test reactions to Alternaria extracts bound significantly higher levels of 125-I-CLF than did sera from allergic children with negative skin tests or from control children. Binding levels in sera from children with hypogammaglobulinemia were significantly less than binding levels in sera from normal children in any age group. Sera from children with selective IgA deficiency bound 125-I-CLF at normal levels. The almost universal occurrence of anti-Alternaria antibodies in children was partly explained by the finding of partial cross-reactivity and/or shared antigens among several fungal species, including A. tenuis, Stemphylium sp., Curvularia sp., and Aspergillus fumigatus. The biological significance of these antibodies is not clear, but the procedures described lend themselves to further investigations.