Abstract
Aim: To investigate the possibility of antenatal sensitisation to respiratory syncytial virus (RSV).
Methods: A total of 36 cord blood specimens were obtained from newborn infants; serum IgA was measured to exclude maternal blood contamination. Cord peripheral blood mononuclear cells were separated and cultured in the presence of either uninfected negative control cells or cells containing ultraviolet (UV) inactivated RSV. Proliferation was assessed by tritiated thymidine incorporation. Supernatant cytokine concentrations were measured using ELISA.
Results: Significantly higher proliferative response rates to UV inactivated RSV were shown in those infants exposed in utero to the RSV epidemic after 22 weeks gestation. UV inactivated RSV stimulation induced significantly higher interferon γ production from specimens with a positive proliferative response (sensitised) than from those with a negative response (not sensitised).
Conclusions: Antenatal sensitisation to RSV occurs in one third of infants exposed to an RSV epidemic at the appropriate time of gestation. This sensitisation is associated with increased interferon γ production, suggesting a type 1 memory response. We hypothesise that priming of fetal T cells to RSV results in a reduced severity of subsequent RSV disease in these individuals and that this will explain much of the clinical diversity of RSV disease.
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Figure 1 .
Antenatal sensitisation to RSV is associated with RSV induced IFNγ but not type 2 cytokine production from cord blood mononuclear cells. Cord blood mononuclear cells from the 18 infants whose mothers were potentially exposed to RSV antenatally from 22 weeks gestation were stimulated with UV inactivated RSV. (A) Infants were divided into two groups: sensitised to RSV antenatally (n = 6, filled circles), or not sensitised (n = 12, open circles) according to whether their cord blood mononuclear cells proliferated in response to UV RSV. IL-4 and IL-10 were not produced in response to RSV. Graph shows individual values and median values. RSV induced IFNγ production was significantly augmented in infants with antenatal sensitisation, compared to those not sensitised (p = 0.039). (B) A significant correlation was observed between RSV specific proliferation (stimulation index) and IFNγ production (r = 0.806, p = 0.029).
Selected References
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