A role of impaired neonatal T cell activation upon late CMV detection

Objective: examine signs of impaired neonatal T cell activation upon late cytomegalovirus (CMV) DNA detection in the blood and urine.

Materials and methods. 147 neonates with non-specific clinical symptoms were enrolled to the study. Peripheral blood lymphocyte subsets were immunophenotyped by using anti-human antibody panel to stain for surface markers CD3, CD4, CD8, CD20, CD3⁺CD28^-, CD3⁺CD28⁺, CD3^–CD28⁺, CD20⁺CD40⁺, CD28, CD40 (IMMUNOTECH, France) for further analysis on a laser flow cytometer Beckman Coulter Epics XL II. CMV infection in 123 neonates was verified by PCR, whereas it was negative in 24 cases. Further, 24 children aged 1.5–3 months negative for CMV DNA during the first month of life were later shown to contain it in the blood and urine samples as well as elevated anti-CMV IgG antibodies allowing to verify CMV infection.

Results. It was found that upon late CMV DNA detection, amount of CD3⁺CD28⁺ T cells in peripheral blood was directly related to count of total CD3⁺ T cells regardless of CD28 expression. Moreover, the peak percentage of CD3⁺CD28⁺ (70–80%) T cells ranged within 85–90%. Whereas children upon early CMV detection the maximum percentage of CD3⁺CD28⁺ T cells was associated with lowered CD3⁺ T cell count (45–55%), it was also paralleled with high CD28 expression (higher than 3%). Importantly, T cells co-expressing CD28+ activation marker necessary for co-stimulation represent one of significant parameters used in diagnostics. Down-modulated CD28 expression abrogating costimulatory signaling and resulting in T cell anergy contributes to developing immunological failure in neonatal CMV infection. The data obtained confirmed importance of cell-cell immune and non-immune interactions for executing anti-CMV immune response within the first months of life. Finally, it is proposed to predict developing CMV infection depending on percentage of CD3⁺ and CD28⁺CD3⁺ T cell subsets in neonates manifested with non-specific clinical signs upon late CMV DNA detection.