Objective:

Early diagnosis of congenital toxoplasma infection is difficult to establish using serological methods. We explored specific T cell immunity to Toxoplasma gondii antigens to identify more accurate diagnostic tests for an early diagnosis of toxoplasma infection in newborns at risk for congenital toxoplasmosis.

Study Design:

T lymphocyte proliferation, interferon (IFN)-γ production and lymphocyte activation antigens expression were evaluated in 23 infected and 65 uninfected neonates at different times, in the first year of life.

Results:

The immunologic tests accurately discriminated when tested≤ 90 and> 90 days of age, respectively and were significantly lower in uninfected than in infected infants: activation antigen CD25, P< 0.001 and P< 0.00001; activation antigen histocompatibility leukocyte antigen (HLA)-DR, P< 0.01 and P< 0.00001; T cell proliferation, P< 0.0001 and P< 0.00001; IFN-γ production, P< 0.001 and P< 0.00001. Evaluation of the specific T cell response allowed identification at 3 months of age or younger, 2 of 23 infected neonates, who had negative serologic tests. Moreover specific T lymphocyte activity increased with age even in neonates undergoing therapy, suggesting that medical treatment does not affect lymphocyte response.

Conclusions:

Evaluation of T cell immunity is important for an early and accurate diagnosis of congenital toxoplasmosis.