Immunophenotypic analysis of lymphocyte subsets in newborns with biotinidase deficiency.

BACKGROUND/AIM Biotin is a vital micronutrient that plays a role in metabolic homeostasis and the regulation of innate and adaptive immune system functions. Biotinidase deficiency (BTD) leads to impairment in biotin-dependent immune functions. This study focused on immunophenotypic analysis of lymphocyte subsets in newborns with BTD. PATIENTS AND METHODS A total of 181 (95 female and 86 male; 114 with BTD and 67 healthy) newborns underwent biotinidase enzyme activity, molecular, and lymphocyte immunophenotyping analyses. BTD is classified into four biochemical phenotypes: profound, partial, heterozygous, and normal. The following lymphocyte subsets were studied in all participants: total B lymphocyte (CD19), total T lymphocyte (CD3), helper T lymphocyte (CD3/CD4), cytotoxic T lymphocyte (CTL) (CD3/CD8), natural killer T lymphocyte (CD16/56), and a T lymphocyte activation marker (HLA-DR). RESULTS The percentages of lymphocyte subsets were similar in newborns with and without BTD. In all newborns with BTD, the mean CD3/CD4 levels were higher in females, while the CD3/CD8 levels were higher in males (p<0.001for each). In female and male newborns, the CD3/CD4 levels were 53.83±9.46 and 16.82±5.19, respectively, and the CD3/CD8 levels were 48.80±8.65 and 21.48±6.02, respectively. A moderate negative correlation was found between CD3/CD4 and CD3/CD8 in female and male newborns (rfemale =-0.488, rmale =-0.574, p <0.001). CONCLUSION This study showed that although there were no differences in the lymphocyte subsets in newborns with BTD, the CD3/CD4 levels were higher in females, and the CD3/CD8 levels were higher in males. In addition, there was a negative correlation between the CD3/CD4 and CD3/CD8 levels in both genders. Although these results indicate sexual dimorphism between CD3/CD4 and CD3/CD8 levels, whether this dissociation is unique to BTD in newborns is not fully clear.