Body fat and circulating leukocytes in children

Objective: To determine the effects of obesity on baseline levels of circulating granulocytes, monocytes, and lymphocyte subtypes in otherwise healthy children. Design: Two group comparison of leukocytes in normal weight control and overweight children. Subjects: In total, 38 boys and girls, ages 6-18 years, divided in two groups: normal weight, (NW, BMI<85th %tile, n=15) and overweight (OW, body mass index (BMI)>85th %tile, n=23). Measurements: BMI obtained from direct measures of height and body mass. Body fat was assessed by DEXA. Complete blood counts (CBC) were obtained by standard clinical hematology methods and surface antigen staining by flow cytometry. Results: The OW group compared to the NW group had increased total leukocytes counts (P=0.011), neutrophils (P=0.006), monocytes (P=0.008), total T (CD3) lymphocytes (P=0.022), and Helper T (CD4⁺) cells (P=0.003). Significant correlations were evident between leukocytes, and BMI percentile, BMI, or percent body fat. Neither lean body mass nor VO_2peak per unit lean body mass were significantly related to any of the leukocytes. Percent body fat and BMI percentile were positively correlated (P<0.05) to total T cells (CD3) and/or helper T cells (CD4⁺). Conclusion: A group of 23 overweight children displayed elevated counts in most types of circulating immune cells, suggesting the presence of low-grade systemic inflammation, a known pathogenetic mechanism underlying most long-term complications of obesity. Our data provide an additional rationale for the importance of avoiding or correcting pediatric obesity.