Activation of T cells in preterm infants with respiratory distress syndrome.

BACKGROUND

Preterm infants with respiratory distress syndrome (RDS) present with systemic inflammation. The role of lymphocytes in RDS is less studied. Activation of lymphocytes could mediate chronic inflammation and development of bronchopulmonary dysplasia (BPD).

OBJECTIVE

To evaluate whether T cells are activated in preterm infants with RDS and whether T cell activation is associated with the development of BPD.

METHODS

Thirty-four infants with RDS [mean gestational age 27.1 (SD 2.0) weeks, birth weight 900 (216) g] were compared with 21 infants without RDS [32.6 (1.4) weeks, 1,697 (406) g]. From blood samples taken on postnatal days 1, 3, and 7, CD4 and CD8 cell counts and their expressions of co-stimulatory molecule CD54 and adhesion molecule CD62L were determined by flow cytometry. In activated cells, expression of CD54 is increased and CD62L is decreased.

RESULTS

As compared with infants without RDS, infants with RDS had less CD4 and CD8 cells on day 3 (both p = 0.02). On day 1 and day 3, RDS was associated with increased CD54 expression on CD4 cells (p = 0.001; p = 0.03) and decreased CD62L expression on CD8 cells (both p = 0.02). Infants with RDS who developed BPD (n = 18) had higher CD54 expression on CD4 cells on day 3 (p = 0.01) and on CD8 cells on day 1 and day 3 (p = 0.01; p = 0.04) as compared with infants without BPD (n = 16).

CONCLUSIONS

In preterm infants, RDS is associated with a lower T cell count and a higher proportion of activated cells. Increased proportion of activated T cells predicts the development of BPD. Systemic T cell activation could mediate inflammation and development of BPD.