Development of Cockroach-Allergic Guinea Pig by Simple Room Air Contamination

Abstract

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.

Experimental Asthma Developed by Room Air Contamination with Cockroach Allergen

“…First, PCA for both IgE and IgGla-likc antibodies was measured by the same method de scribed in our earlier study [22,23]. Briefly, thawed serum was divid ed into 2 aliquots.…”

Contractile Responses to Allergen and Cholinergic Stimulation in Bronchus and Trachea of Cockroach Allergen-Sensitized Guinea Pigs

“…Unlike our CRa aerosol sensitization a great majority of other animal models were immunized with an allergen given intraperitoneally and often with an adjuvant [9, 10, 11, 14]. In our study the state of immunization of guinea pigs was proven by the presence of anti-CRa IgG1 [16, 17, 18] as well as by the cellularity in BAL fluid (table 1). Yet, our findings, normal contractile response to ACh and leukocytosis in BAL, closely resemble the report by Wills-Karp et al [12], whose guinea pigs were intraperitoneally immunized with OA.…”

“…Such antigen-specific contractions of asthmatic airways are results primarily from the actions and interactions of released anaphylactic mediators, preformed as well as newly generated, e.g., histamine and LTs, from mast cells via antigen-anaphylactic antibody interaction. The antibody in this model is the CRa-specific IgG1 but not IgE [16, 17, 18]. …”

“…The aerosol exposure was carried out for a period of 45 min repeated twice a day, 5 days a week, for 4 weeks. After 4 weeks of immunization, development of anaphylactic sensitivity to CRa was confirmed by both allergic skin test and PCA test as described [16, 17, 18]. Five days after the last aerosol exposure, the asthmatic responses in vivo were measured using a double chamber plethysmograph following CRa challenge (1 mg/ml × 10 ml) in conscious state as described [18].…”

“…Previously, our laboratory reported that guinea pigs exposed chronically to airborne CRa developed allergic sensitization and that subsequent CRa challenge induced asthma-like lung function changes [16, 17, 18]. As a part of the study to elucidate the mechanisms of CRa-induced asthma, the authors investigated the contractile responses of airway smooth muscles in vitro to cholinergic stimulants, ACh and electrical field stimulation (EFS), using tracheal (TSM) and bronchial (BSM) smooth muscle rings, isolated from the guinea pigs chronically immunized by aerosolized CRa or from nonimmunized guinea pigs and passively sensitized with sera of CRa-immunized guinea pigs.…”