Decline in total serum IgE after treatment for tuberculosis

Background. Infection with Mycobacterium tuberculosis induces a type-1 immu ne response, whereas intestinal parasites elicit a type-2 response. Given t hat type-1 and type-2 responses inhibit each other, we investigated. if M t uberculosis downregulates serum IgE, a marker of a type-2 response. Methods. A prospective study was done in the Western Cape Province of South Africa, where tuberculosis and intestinal-parasite infection are common. T otal serum IgE was determined for 37 controls and for 33 adolescent patient s at presentation with tuberculosis and after successful completion of trea tment. IgE specific for ascaris and allergens were measured in a subset of these individuals. Mantoux skin tests were done on 35 controls and on 31 pa tients at diagnosis. Findings. Total IgE concentrations were high in controls (mean 313 kU/L) an d in patients before treatment (mean 457 kU/L, p = 0.085) and declined in a ll patients following successful treatment (mean 175 kU/L, p < 0.0001). Pos ttreatment IgE concentrations did not differ from concentrations in control s. Ascaris-specific IgE was lower in controls (mean 1.73 kU/L) than in pati ents before treatment (4.62 kU/L, p = 0.023) and was 2.39 kU/L in patients after treatment (p = 0.0625). Tuberculin induration correlated inversely wi th IgE in patients but not in controls. Interpretation. Infection with M tuberculosis as such is not incompatible w ith a prominent IgE response. IgE concentrations decreased after successful treatment of tuberculosis, showing that IgE concentrations in human beings can be downregulated under these circumstances, presumably due to enhancem ent of a type-1 response.