Background: Obesity as a global public health problem is increasing in prevalence. Reports showed that obese children are more liable to infection than lean ones; it was claimed that obese subjects have altered peripheral blood total lymphocyte counts in addition to reduced lymphocyte proliferative response to mitogen stimulation as well as dysregulated cytokine expression.Objective: This study aimed to evaluate the effect of childhood obesity on cell mediated immunity as indicated by peripheral blood lymphocyte phenotyping.Methods: We enrolled 30 school-aged children (mean age 10±3.27 years). They comprised two groups; 20 obese children with a mean body mass index (BMI) of 39.2± 12.5 and 10 matched control subjects with mean BMI of 18.4± 1.9. They were subjected to detailed anthropometric evaluation including weight, height, and waist hip ratio in addition to calculation of BMI, complete blood counting, and flow cytometric assessment of T-helper (CD4), T-cytotoxic/suppressor (CD8), and natural killer (CD56) cell counts .Results: The absolute lymphocyte (CD3) and natural killer cell (CD56) counts were comparable in both groups. However, the CD4%, CD8%, CD4/CD8 ratio were significantly lower in the obese children (p=0.02, 0.03, 0.015 respectively). A significant negative correlation could be elicited between the CD4 count and bodyweight, BMI, and hip waist ratio (p = 0.00); the same was observed for CD4/CD8 ratio (p = 0.00). On the contrary, CD8 correlated positively to the bodyweight, BMI, and waist hip ratio (p = 0.00 for each) .Conclusion: Obesity has an impact on lymphocytic subset counts and further studies are needed to assess its effect on their function.Keywords: obesity, children immunology; CD markers; lymphocytes; BM
