Asthma is frequently associated with inhalant sensitivities, particularly allergens of indoor environment. The aim of the study is to determine whether an indoor allergen, cockroach (CRa), can induce guinea pig sensitization without adjuvant or special manipulation. Six regimens were used in sensitizing guinea pigs by CRa aerosols: low daily (C-I), low intermittent (C-II), high intermittent (C-III), maximum intermittent (C-IV), high daily (C-V) and high alternate day (C-VI) doses, and results were compared with that of intraperitoneal sensitization (C-VII). Also studied was a role of CRa in the aerosol ovalbumin (OA) sensitization in comparison with placebo and an adjuvant, Al(OH)₃. Reaginic guinea pig antibodies, anti-CRa-IgGla-like (IgGla) and IgE-like (IgE), were measured by passive cutaneous anaphylaxis (PCA). Results show that IgGla was produced only in high-dose aerosol groups, C-V and C-VI, but no IgE in all aerosol groups. The antibody was detected on day 22 (C-V) and day 19 (C-VI) and sustained till day 52 (titers 1:20 to 1:200). The preliminary pulmonary function measurements revealed that the sensitized animals (C-VI) showed a decreased ventilatory function upon CRa challenge. Aerosolized OA sensitization also produced anti-OA-IgGla in high intermittent regimens. In addition, PCA titers (anti-OA-IgGla) in OA-sensitized animals were not influenced by pretreatment with CRa, Al(OH)₃, or placebo. Thus, the study indicates that simple aerosolized CRa contamination in a chamber makes guinea pigs cockroach-sensitive and become asthmatic. Yet, CRa does not enhance other allergen sensitization.

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