American cockroach Cr-PI allergen induces lymphocyte proliferation and cytokine production in atopic patients

Background Previous studies have shown cockroach-induced antigen-specific IgE-mediated asthma. In cockroach-infested areas, more then 50% of asthmatic subjects may have positive skin reactions to this allergen. Partial purified Cr-PI allergen from American cockroaches contains allergens with molecular weights of 72 and 78 kDa; however, little is known about its effect on the lymphocyte proliferation and cytokine production. Objective IgE synthesis is known to be regulated by interleukin-4 (IL-4) and interferon gamma (IFN gamma). Therefore, we studied Cr-PI allergen-induced cytokine production in atopic patients and healthy normal controls to understand each factors' role in the disease. Methods Peripheral blood mononuclear cells (PBMC) from cockroach skin-sensitive patients and controls were stimulated with mitogen and Cr-PI for proliferative response and cytokine production. Cr-PI antigen-specific T-cell cultures of atopic patients and healthy normal controls were used to test Cr-PI-induced proliferation and cytokine mRNA expression. Results PMBC of atopic subjects showed a significantly (P < 0.01) higher stimulation index for Cr-PI induced proliferation (SI = 11.8 +/- 3.7) when compared with that of non-atopic subjects (SI = 4.1 +/- 0.8) and cord bloods (SI = 2.1 +/- 0.4). Cr-PI-induced IL-4 was observed only in the PBMC of atopic patients, whereas Cr-PI-induced IFN gamma was detected in both atopic patients and normal controls. Likewise, Cr-PI-induced IL-4 mRNA expression in T-cell cultures was detected in all atopics but only one of nine controls. Conclusion IL-4 mRNA expression and IL-4 production in PBMC and T-cell cultures of atopic patients showed good correlation with clinical symptoms, skin-reactivity, specific IgE and proliferative response to Cr-PI. These results suggests that cockroach allergen may be a hidden cause of asthma and other atopic diseases.