Lymphocyte subpopulations in full-term septic neonates

Purpose: To estimate the absolute leukocyte and lymphocyte counts and relat ive and absolute sizes of CD19+ B lymphocytes, CD3+, CD4+, CD8+ and CD3+/HL A-DR+ T lymphocytes in full-term septic neonates and the influence of some perinatal risk factors on these lymphocyte subsets. Methods: Twenty-one septic and mechanically ventilated full-term neonates ( 13 boys and eight girls) and 15 healthy full-term neonates born vaginally w ith an Apgar score >9 and without hyperbilirubinemia were investigated. Two -color flow cytometric immunophenotyping with appropriate antibody panels u sing lysed whole vein blood was performed. Results: The mean relative and absolute sizes of CD19+ B lymphocytes, CD3+/ CD8+ and CD3+/HLA-DR+ T lymphocytes in septic neonates did not differ signi ficantly from control. In contrast, the mean relative sizes of CD3+ and CD3 +/CD4+ T lymphocytes and the CD4+/CD8+ ratio in septic neonates were signif icantly higher than in healthy neonates. With regard to the absolute size i n septic neonates, only CD4+ T cells were significantly higher compared wit h the control group. Perinatal risk factors (birth asphyxia, gestation and delivery complications) had no significant effect on the relative and absol ute counts of all estimated lymphocyte subpopulations in septic neonates. Conclusions: Increases in the relative sizes of CD3+ and CD3+/CD4+ T lympho cytes and the CD4+/CD8+ ratio in full-term septic neonates provides importa nt information about changes in cell-mediated immunity during the early neo natal period.