COMPLEMENT ACTIVATING AGENTS IN ALLERGENIC EXTRACTS

Objective: Extracts of environmental allergens, moulds and plant polle ns are known to consume haemolytic complement (huC) in human serum in vitro through the antibody-independent engagement of the first compone nt C1 of the classical pathway. The present work was undertaken to est ablish the nature and characteristics of the complement activating age nts in allergenic extracts and to probe their relationship with the Ig E-binding allergens. Materials and Methods: A large series of differen t >10 kDa allergenic products was investigated for their capacity to c onsume haemolytic complement in the sera of allergic patients with spe cific anti-allergen IgE antibodies, as well as in normal control sera. UV-spectroscopy was used for categorizing the non-protein components in the extracts. Results: The experiments confirmed that huC is consum ed in an antibody-independent fashion and in a qualitatively similar, but quantitatively distinct manner. The ratio of the complement activa ting potencies among the different allergenic preparations thereby rem ained constant and independent of the serum source, while an overt rel ationship with specific IgE-antibodies could not be established. UV-sp ectroscopy of the allergenic preparations revealed the presence of che mical decomposition products in nearly every extract and roughly in pr oportion to the complement activating potencies. Conclusion: The data support the idea that huC-activation by traditional allergenic extract s is mainly due to by-stander degradation products of the melanoidin ( Maillard) or tannin type, which may or may not occur in physical assoc iation with the IgE-binding protein allergens.