Antigens and allergens in Dermatophagoïdes farinae mite. I. Immunochemical and physicochemical study of two allergenic fractions from a partially-purified Dermatophagoïdes farinae mite extract.

Abstract

The fractionation of a partially-purified extract of Dermatophagoïdes farinae mite culture has been undertaken by gel filtration. Two fractions were isolated. One, P25, is a protein-rich fraction with mol. wt about 25,000. The other, GP8, is a polysaccharide-rich fraction with mol. wt around 8,000. By crossed immunoelectrophoresis, we detected eleven antigens in the partially-purified dialysed D. farinae extract (Df 80d) as well as in P25 fraction. One of them, ag 11, seems the most important allergen since in crossed-radio immunoelectrophoresis experiments it displays the faster radiostaining, implying that it binds the greatest part of the mite-specific IgE present in a pool of sera from mite-sensitive patients. By crossed-line immunoelectrophoresis, we demonstrated the absence of ag 11 in GP8, in which only ag 5 and ag 6 were identifiable. By radioalloergosorbent tests (RAST), it was found that P25- and GP8- coated paper discs can fix specific IgE induced in the majority of D. farinae sensitive patients. Defining a 'major allergen' as an allergen to which the majority of sensitive patients develop specific IgE, both P25 and GP8 do appear to contain at least one major allergen. By RAST inhibition method, using Df 80d as a solid phase, the allergenic activity of P25 appeared as slightly higher than that of Df 80d, whereas GP8 displayed a very weak inhibitor capacity. Thus, the allergic specificity of GP8 differs from that of Df 80d or P25.