Characterization and partial purification of the cockroach antigen in relation to housedust and housedust mite (D.f.)...

Allergens in crude cockroach antigens (CRa) have not been well defined. In order to characterize the CRa, the authors partially purified CRa by gel filtration (G-75) and analyzed it by polyacrylamide electrophoresis (PAGE) and allergy skin testing (AST). Hyperimmune serum was produced against CRa in rabbit (R anti-CRa) and used for immunoelectrophoresis (IEP), double immunodiffusion (DID), crossed immunoelectrophoresis (CIE), and crossed radio immunoelectrophoresis (CRIE) to further characterize the CRa. The crude CRa contained 9 and 15 precipitating arcs by IEP and CIE, respectively. Indirect CRIE revealed that CRa contained nine to 15 different allergens. There were no lines of identity between the CRa and housedust mite (D.f.) or between the CRa and commercial housedust by DID or IEP. Autologous housedust of cockroach asthmatic subjects showed lines of identity with the CRa. Fractionation of CRa on a Sephadex G-75 column chromatography showed two distinct peaks (B1 and B2) separated by a broad valley. The high molecular fraction B1 was most allergenic (100%) and contained three antigens of high molecular weight. These three antigens were identifiable by the techniques of IE, CIE, and DID. B2, the low molecular fraction (molecular weight less than 13,000 dalton) contained minor allergen(s). B2 elicited positive AST in 55% of cockroach-sensitive individuals, but it was not detected by IEP, CIE, nor by DID.