A switch towards Th2 during serological rebound in children with congenital toxoplasmosis

Serological rebounds occur frequently in patients with congenital toxoplasm osis, but remain poorly understood. A link between Th1 and Th2 cytokines an d the pathophysiology of infectious diseases has been reported. Production of interferon-gamma (IFN-gamma) and IL-4 in supernatants of whole blood aft er in vitro specific Toxoplasma gondii stimulation and serum-specific IgE l evels were studied in 31 congenitally infected children. IFN-gamma was prod uced at higher levels by lymphocytes from children with stable congenital t oxoplasmosis (n = 18) than From children showing serological rebound (n = 1 3) (P < 0.04). Conversely, supernatants from children with serological rebo und showed higher levels of IL-4 than those from children with stable conge nital toxoplasmosis (P < 0.03). The polarized Th2 response was confirmed by a greater (IL-4:IFN-gamma)x 100 ratio (P<0.0001) and production of T. gond ii-specific IgE in six out of 13 children showing serological rebound. Thes e results suggest a role of Th2, cytokines in destabilization of congenital toxoplasmosis and perhaps in local reactivation of the parasite.