Aims Evaluation of the percentage and absolute number of selected T lymphocytes subsets in premature neonates regarding their BW, GA, sex, mode of delivery, Apgar score and respiratory failure, in relationship to congenital infection.

Material 63 prematures (40 boys, 23 girls): 41 infected preterm (22 septic, 19 pneumonic) and 22 without infections.

Results Infected prematures, without respiratory failure had higher (p<0,05) mean number of WBCs (14,6+/−5,2 G/l), lymphocytes (6,8+/−2,6), CD3+ (4,24+/−1,74) , CD4+ (3,55+/−1,62), CD8+ (1,49+/−0,87) than infected babies with respiratory insufficiency (respectively: 10,7+/−5,3 5,0+/−2,5, 2,53+/−1,23, 1,88+/−0,96). The mean percentages of CD3+ (66,1+/−10,1%) and CD4+ (48,6+/−12,1%) were significantly higher in infected premature neonates without respiratory disorders than in infected babies without this complication (51,8+/−13,6%, 40,2+/−12,3%). The mean percentage (10,1+/−3,5%, range 2–19%), and mean number of CD25+ (0,52+/−0,22G/l) were significantly higher in septic and pneumonic preterm (p<0,02) than in preterm without infection. The mean percentage of TCR gammadelta in infected babies (3,8+/−2,3%) were significantly lower (p<0,04) than preterms without infection (2,8+/−2,2%). In infected preterms with birth asphyxia mean percentage of TCR alfabeta (64,5+/−10,5%) was higher (p<0,04) than in infected babies born in good condition (52,9+/−12,4%).

Conclusions In preterm neonates congenital infections complicated by respiratory failure influence on decrease of mean values of CD3+ and CD4+ and decrease of CD8+ T lymphocytes. Congenital infections promote the increase of values of CD25+ and TCR gammadelta T lymphocytes. Estimation of the value of lymphocytes T subsets, especially CD25+ and TCR gammadelta, may facilitate the diagnosis of infection in prematures, even with negative cultures.