Aberrant ICOS + ‐T cell differentiation in women with spontaneous preterm labor

Problem Recent studies revealed appropriate differentiation of recent thymic emigrant ( RTE )‐regulatory T cells (Tregs) to be crucial for maintaining healthy pregnancy. Currently, the role of responder T cells (Tresps) is not known. Method of study Six‐color flow cytometric analysis was used to detect differences in the differentiation of highly proliferative inducible co‐stimulatory ( ICOS ) + ‐ RTE ‐Tregs/Tresps and apoptosis‐sensitive ICOS − ‐ RTE ‐Tregs/Tresps into mature naïve ( MN )‐, CD 31 + ‐memory and CD 31 − ‐memory Tregs/Tresps in women with spontaneous preterm labor ( sPL ) compared to healthy pregnancy. Results Healthy pregnancy was characterized by an increased differentiation of ICOS + ‐ and ICOS − ‐ RTE ‐Tregs, as well as ICOS + ‐ RTE ‐Tresps via CD 31 + ‐memory Tregs/Tresps into CD 31 − ‐memory Tregs/Tresps. Women with sPL showed an early interruption of RTE ‐Treg/Tresp differentiation. Instead, ICOS + ‐ MN ‐Tresps and partly ICOS − ‐ MN ‐Tregs differentiated into CD 31 − ‐memory Tregs/Tresps, causing a significant reduction of both ICOS + ‐Tregs and ICOS + ‐Tresps, but an increase of ICOS − ‐Tresps within total CD 4 + ‐T‐helper cells. Conclusion Aberrant differentiation of ICOS + ‐T cells is associated with sPL .