A comparative study on cockroach and ovalbumin sensitizations and challenge responses in Hartley guinea-pigs

The role of allergens in asthmatic inflammation is not clearly understood. To elucidate the mechanism of cockroach allergen (CRa)-induced airway disea se, we studied three groups of Hartley guinea-pigs sensitized to control, o valbumin (OA) or CRa, Parameters measured were anaphylactic antibodies by a llergy skin test (AST), PCA assay and Western blot, changes in specific air way resistance (SRaw), analysis of bronchoalveolar lavage (BAL) and contrac ture responses of tracheal muscle (TSM) to non-specific and specific stimul i, in vitro. Both OA and CRa animals showed a similar allergic sensitizatio n (AST and PCA), while Western blot identified several reaginic bands in CR a group compared to a single band in OA group. SRaw illustrated that CRa in duce dual-asthmatic responses (416) in the CRa group, whereas OA induce onl y an early asthmatic response (3/6) in the OA group (P < 0.01). The average total leukocytes in BALF of the CRa were 27.0 x 10(6), mostly neutrophils and eosinophils, while those of the OA showed 3.5 x 10(6), mostly eosinophi ls, respectively (P < 0.0001). TSM responses to non-specific stimuli were s imilar in both groups (P > 0.1), while the antigen-specific TSM contraction s were more brisk in the OA group than those of CRa group (P < 0.001). Thus , the study indicates that both CRa and OA sensitize guinea-pigs, yet CRa i nduces more severe and persistent late-phase inflammation than OA. This app ears to be related to an influx of neutrophils rather than anaphylactic bro nchospasm. <(c)> 2001 Elsevier Science B.V. All rights reserved.