OBJECTIVETo investigate the influencing factors for lymphocyte subsets in children 0 to 6 years of age.

METHODSUmbilical artery blood samples from 45 healthy full-term infants and venous blood samples from 79 healthy children between 0 and 6 years were collected. According to the methods of delivery, the full-term infants were divided into vaginal delivery group (n=22) and cesarean section group (n=23). Healthy children were divided into different age groups: 28 days to 12 months (n=25), 1-3 years (n=26), and 3-6 years (n=28). Lymphocyte subsets were examined by flow cytometry. The influencing factors including delivery method, sex, and age, which might have an effect on the lymphocyte subsets, were analyzed.

RESULTSThere were significant differences in T and Ts cell counts, percentage of B cells, and percentage and count of natural killer (NK) cells between the full-term infants of vaginal delivery and cesarean section (P<0.05). The absolute counts and percentages of different lymphocyte subsets showed no significant differences between males and females in healthy children (P>0.05). The counts of all lymphocyte subsets except Ts and NK cells varied significantly between different age groups (P<0.05).

CONCLUSIONSLymphocyte subsets in children under 6 years of age are more profoundly affected by age. Delivery method is also a contributing factor in newborn infants. The reference range of lymphocyte subsets in children should be established for different age groups.