Abstract

QUEIROZ, D.A.O. et al. Immune response to respiratory syncytial virus in young Brazilian children. Braz J Med Biol Res [online]. 2002, vol.35, n.10, pp. 1183-1193. ISSN 1414-431X.  http://dx.doi.org/10.1590/S0100-879X2002001000011.

We have evaluated the cellular and humoral immune response to primary respiratory syncytial virus (RSV) infection in young infants. Serum specimens from 65 patients £12 months of age (39 males and 26 females, 28 cases <3 months and 37 cases ³3 months; median 3 ± 3.9 months) were tested for anti-RSV IgG and IgG subclass antibodies by EIA. Flow cytometry was used to characterize cell surface markers expressed on peripheral blood mononuclear cells (PBMC) from 29 RSV-infected children. There was a low rate of seroconversion in children <3 months of age, whose acute-phase PBMC were mostly T lymphocytes (63.0 ± 9.0%). In contrast, a higher rate of seroconversion was observed in children >3 months of age, with predominance of B lymphocytes (71.0 ± 17.7%). Stimulation of PBMC with RSV (2 x 10⁵ TCID₅₀) for 48 h did not induce a detectable increase in intracellular cytokines and only a few showed a detectable increase in RSV-specific secreted cytokines. These data suggest that age is an important factor affecting the infants' ability to develop an immune response to RSV.

Keywords : Respiratory syncytial virus; Peripheral blood mononuclear cells; Young children; Surface antigens; Cytokines.