Abstract 177: Obesity Alters Circulating T Cell Profile in Female African American Teenagers

Extensive evidence supports a role of the immune system in the development of cardiovascular disease. Moreover, at-risk cardiovascular patients display pro-inflammatory mediators years before disease is openly declared. Given the greater prevalence of obesity among African Americans, we hypothesized that obesity leads to alterations in the circulating immune cell profile in a population of African American teenagers. Lean (BMI < 50th percentile) and obese (BMI ≥ 95th percentile) African American teenagers (14-20 years-old; n=13-22/group) of both genders were recruited from public schools of Augusta, GA. Cell differentials and circulating specific immune cell populations were analyzed by fluorescence-activated cell sorting or FACS flow cytometry. Whole blood cell counting with five differentials (including neutrophils, lymphocytes, monocytes, eosinophils and basophils) were conducted in all the subjects. We did not observe any significant difference in the proportion of these five major cell types between obese cases and lean controls either in the overall samples or in the sex-stratified analysis. Obese African American females presented significantly elevated percentages of circulating T lymphocytes (CD3+ cells: (34.6 ± 1.8% vs. 28.1 ± 2.2%; p<0.05) and T helper cells (CD4+ cells: 29.37 ± 1.5% vs. 26.4 ± 1.5%; p<0.05) when compared to lean females. African American obese females also tended to have greater percentages of activated CD3+ cells (CD3+/CD69+ cells) than lean females, although significance was not reached (0.67 ± 0.2% vs. 0.39 ± 0.1%). No significant differences were found between African American male obese and lean subjects in any of the circulating immune cell populations. In conclusion, obese female African American teenagers present higher circulating percentages of CD3+ and CD4+ cells than their lean counterparts without changes in the percentages of total lymphocytes. These results suggest that certain subsets of T cells may be key players in obesity-related immune disorders. The identification of the obesity-related T-cell activation may provide new etiologies and biomarkers for obesity-induced cardiovascular disease.