High incidence and heterogeneity of functional defects of the alternative pathway of complement among atopic children.

Two separate functional defects of the alternate pathway of complement (defective yeast opsonisation and defective rabbit erythrocyte lysis) are very frequent (of the order of 55% for the former and 35% for the latter) among atopic children and their unaffected relatives. The defects are independent of each other and of sex, age, season of sampling, type of atopic syndrome and IgE level. The alternative pathway initiation mechanism is probably involved in both defects.