ANTIGENS AND ALLERGENS IN DERMATOPHAGOIDES-FARINAE MITE .2. PURIFICATION OF AG 11, A MAJOR ALLERGEN IN DERMATOPHAGOIDES-FARINAE

  • 1 January 1982
    • journal article
    • research article
    • Vol. 46  (4) , 679-687
Abstract
(NH4)2SO4 precipitation and DEAE chromatography is an efficient way of purifying Ag 11, the main allergen in D. farinae mites, which has already been characterized by crossed radioimmunoelectrophoresis. At 60% of saturation in (NH4)2SO4, a precipitate is formed which, dissolved and dialyzed was named fraction A 60. It is mainly composed of Ag 11. In the fraction DE obtained by DEAE chromatography of the (NH4)2SO4 fraction A 60, Ag 11 appears homogeneous on crossed-immunoelectrophoresis. Isoelectrofocusing results indicate an average isoelectric point near neutrality in agreement with the non-absorption of Ag 11 on the DEAE cellulose at a weak ionic strength (0.01, at pH 7.2). By sodium dodecyl sulfate polyacrylamide gel electrophoresis and gel filtration at Ag 11 has a MW of 28,000. Ag 11 appears as a single polypeptidic chain with numerous dithio-bonds implying a highly folded and resistant structure. Oligosaccharides could be present as constituting molecules and contaminating ones as was assumed for hexosamines. The results are discussed with reference to a similar study performed on the major allergen of D. pteronyssinus. The allergenic properties of Ag 11 as present in fraction DE were tested by RAST[radioallergosorbent test]-based methods. Fraction DE is an inhibitor as good and Df 80d and when it is coated on paper discs it can bind specific IgE in sera from the majority of mite sensitive patients. Ag 11 is apparently a major allergen from D. farinae.