IgG subclass antibody responses to birch pollen in sibling pairs discordant for atopy

Birch pollen allergen specific IgG and IgE antibodies were analysed in the sera of fourteen sibling pairs discordant for atopy. In addition, eight unr elated children free of atopic disease were included in the study. The pres ence of Bet v 1 specific antibodies in the sera were analysed by an immunob lotting assay. All but one (13/14) of the atopic children had detectable an ti-Bet v 1 antibodies of the IgG1 and IgG4 subclasses. The child lacking Ig G1 and IgG4 antibodies to Bet v 1 was the only allergic child lacking IgE t o Bet v 1. In contrast, only one of the non-atopic siblings (1/14) displaye d detectable IgG1 antibodies to Bet v 1. Furthermore, among the non-atopic siblings none (0/14), had detectable IgG4 antibodies to Bet v 1. In the unr elated control group no detectable IgG1 or IgG4 anti-Bet v 1 were detected (0/8). Thus of the non-atopic children only one out of 22 children displaye d IgG1 anti-Bet v 1 antibodies. Taken together, it appears that the non-ato pic children in general have no/low allergen specific IgG to birch pollen.