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Th2 intracellular cytokine profile in children with respiratory syncytial virus (RSV) infection

RSV may induce asthma like symptoms in children with lower respiratory tract infection and these children may be more susceptible to development of allergic disease later in life. we have previously shown an overexpresssion of CD23 antigen (low-affinity IgE receptor) on B cells during acutephase of RSV infection, accompanied with the presence of RSV-specific IgE and IgG4 antibodies. IncreasedCD23 expression and isotype switch to IgE and IgG4 is directly connected with IL-4 production. To confirm the hypothesis that RSV may cause Th2 type of immune response, here we investigated the intracellular cytokine profile in peripheral blood lymphocytes from 34 children (age 2-17 months) with bronchiolitis caused by RSV (mAbs detection and RSV isolation from nasopharyngeal secretion). After in vitro lymphocyte stimulation with PMA ( 13-phorbol myristat acetate), ionomicin and BFA( brefeldin A) the presence of intracellular IL-4 (Pharmingen, USA) and IFN-gama (Becton Dickinson, Germany) in CD4 and CD8 lymphocytes were determined by three-colour cytometry (Facscalibur, Becton Dickinson, USA). In the group of RSV infected children we found significantly more IL-4 positive lymphocytes in total lymphocyte population ( 6.9+5.2) than in healthy age matched children (0.8+0.5). Elevated percentages of IL-4 positive cells was found among CD4 (3.7+2.9) and CD8 (5.9+5.2) lymphocyte subpopulations. The synthesis of INF-gama in lymphocytes from RSV infected children was very low, and did not differ from controls. Our data provide direct evidence that RSV infection has pathological influence on cytokine production, focusing immunological reaction in the TH2 direction and that these changes can be monitored at the level of peripheral blood lymphocyte analyses.

Th2; intracellular cytokine profile; children; respiratory syncytial virus (RSV)

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