Eosinophilia and progression to active tuberculosis in HIV-1-infected Ugandans

It has been suggested that type 1 immune responses protect against tuberculosis (TB), while type 2 responses, such as those induced by helminths, may suppress protective responses and increase susceptibility to TB. Factors associated with progression to active TB were investigated in a cohort of HIV-1-infected Ugandan adults, a group at high risk of TB. High rates of subsequent progression to active TB were associated with eosinophil counts greater than or equal to 0.4 x 10(9)/L at enrolment. Eosinophilia at enrolment was associated with male gender, low socio-economic status, high CD4+ T cell counts, and schistosomiasis, but adjusting for these factors did not explain the association of eosinophilia with progression to active TB (adjusted rate ratio = 2.76, P = 0.004). Eosinophilia is most likely to be indicative of a type 2 immune response induced by helminth infection in this Ugandan cohort, but the mechanism of the observed association between eosinophilia and risk of TB remains to be determined.