RESUMO
BACKGROUND: A type 2 immune response, characterized by high levels of interleukin-4 and immunoglobulin E synthesis is a hallmark of respiratory allergic diseases. Individuals infected with human T-lymphotropic virus type I (HTLV-I) virus have spontaneous T-cell proliferation and increased interferon gamma production, which are immunological functions associated with a type 1 immune response. OBJECTIVE: To determine the frequency of asthma and rhinitis symptoms and immediate skin reactivity to aeroallergens in HTLV-I infected individuals, compared with noninfected subjects. METHODS: Cross sectional study of 101 HTLV-I infected and 101 control uninfected blood donors, assessed by enzyme-linked immunosorbent assay and Western blot assays. The subjects were age and sex-matched, identified as presenting allergy history by questionnaire, which was complemented by a complete clinical examination and skin prick tests for aeroallergens. RESULTS: The frequency of atopy was lower in infected than uninfected subjects, 14.9 and 29.7% (P = 0.017), respectively. Skin reactivity to Dermatophagoides pteronissynus, Dermatophagoides farinae and Blomia tropicalis were the most frequently observed among all the tested antigens in both groups. Skin reactivity to histamine was also reduced in the infected individuals compared with uninfected subjects (medians 4.0 vs 5.0, respectively; P < 0.0001). Infection by HTLV-I was found to be a factor of protection to atopy (RP 0.44; P = 0.005). CONCLUSIONS: The HTLV-I infection reduces the frequency of respiratory allergy and skin reactivity to aeroallergens.