1997 年 46 巻 3 号 p. 195-199
We tried to evaluate the role of IgG antibodies in the wheal and flare reaction of infantile atopic dermatitis by in vivo skin-sensitizing methods. Sera from 49 patients under 6 years of age were heated at 56°C for 30min to inactivate IgE antibodies, according to previous reports. Two-fold serial dilutions of the heated serum were injected intracutaneously in both forearms of a non-allergic recipient. One hour later, the whole egg antigen (1:1000) was injected in the serum transfer sites of an arm and the reaction was read at 15min (IgG Prausnitz-Küstner (P-K) test). Immediately afterwards, a raw hen's egg was swallowed by the recipient and the serum transfer sites of the other arm were observed for 2h (oral IgG P-K test). Three patients under 1 year of age showed an immediate wheal and flare reaction in the IgG P-K test, but none of the patients showed a positive reaction in the oral IgG P-K test. The patients with a positive IgG P-K test had an IgE radioallergosorbent test (PAST) score >4 to egg white and a positive IgE P-K titer of >28 to whole egg antigen. Two patients showed a positive reaction to the oral IgE P-K test to raw egg ingestion. Ovalbumin-specific IgG1, IgG3 and IgG4 antibodies were assayed in 20 patients. IgG1 and IgG3 antibodies were significantly increased in two patients with a positive IgG P-K test, while levels of the IgG4 antibody in positive patients were not significantly increased in comparison with levels in negative patients. In conclusion, these results suggest that the IgG antibody may play a role in the immediate type allergic reaction in infantile atopic dermatitis.