T cell cytokine responses to stimulation with Ureaplasma parvum in pregnancy

•Vaginal colonisation with Ureaplasma spp. is common.•Ureaplasma spp. are known to cause inflammation-driven preterm birth.•Ureaplasma parvum stimulation of whole blood increases the frequency of IFNγ-positive CD3+CD4+ T cells, particularly for colonised women.•Ureaplasma parvum stimulation of whole blood increases the frequency of IFNγ-positive CD3+CD4‐(CD8+) T cells, regardless of vaginal colonisation status .

Ureaplasma spp. are a common vaginal microorganism causally linked to inflammation-driven preterm birth (PTB). The nature of the immune response to Ureaplasma spp. may influence PTB risk. This study sought to define maternal T cell cytokine responses to in vitro stimulation with Ureaplasma parvum serovar 3 (UpSV3) in vaginally colonised (UP+) and non-colonised (UP−) pregnant women. Whole blood flow cytometry demonstrated an increase (p = 0.027) in the baseline frequency of IFNγ-positive CD3+CD4−(CD8+) T cells in UP+ women. UpSV3 stimulation resulted in a significant and specific increase (p = 0.001) in the frequency of IFNγ-positive CD3+CD4−(CD8+) T cells, regardless of vaginal colonisation status. UpSV3 stimulation also increased the frequency of IFNγ-positive CD3+CD4+ T cells, particularly in the UP+ group (p = 0.003). This is the first published study to examine T cell responses to Ureaplasma spp. exposure. Future appropriately-powered studies are needed to assess whether insufficient priming or a loss of tolerance to Ureaplasma spp. is occurring in UP+ women at risk of PTB.