Activation of the classical pathway of human complement in vitro by house-dust extracts is caused by IgM antibodies to polysaccharide antigen(s) and is not related to atopy.
The mechanism of activation of the classical pathway of human complement by house-dust extracts and its relevance to atopic disease was studied. Our results confirm that for most sera of adults, house-dust extract is, on a weight basis, a more potent C-activator than aggregated human IgG or lipopolysaccharide (endotoxin). Naturally occurring IgM antibodies directed against ubiquitous polysaccharides appeared to be the dominant factor in the C1 activation by house-dust extracts in human sera. Large variations were found between sera with respect to the concns of these IgM antibodies as measured by C1 activation or fixation of haemolytic complement. The IgM antibody titre was, however, not associated with atopic disease. Consequently, we do not support the hypothesis put forward by Berrens et al. (1978) (Allergol. Immunopath. 6, 45-54) that there might be a relation between atopy and enhanced reactivity of serum complement with allergenic extracts. More than 90% of the C-activating potential of allergen extracts like house dust was found in the fractions with high mol. wt material (mol. wt greater than 100 K). Therefore, these antigens are easily separated from the known IgE-binding major allergens of house-dust mite and cat dander.
Van Der Zee
J S
JS
Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam.
Van Swieten
P
P
Aalberse
R C
RC
D000293:Adolescent; D000328:Adult; D000941:Antigens / Q000032:analysis; D001419:Bacteria / Q000302:isolation & purification; D003167:Complement Activation; D003172:Complement C1 / Q000276:immunology; D003168:Complement Fixation Tests; D003171:Complement Pathway, Classical; D004391:Dust; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology*; D008875:Middle Aged; D008970:Molecular Weight; D011134:Polysaccharides / Q000276:immunology*; D012221:Rhinitis, Allergic, Perennial / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal
D000941:Antigens; D003172:Complement C1; D004391:Dust; D007075:Immunoglobulin M; D011134:Polysaccharides