T‐Helper Type 1 Bias in Healthy People Is Associated With Cytomegalovirus Serology and Atherosclerosis: The Multi‐Ethnic Study of Atherosclerosis

BACKGROUND Although T-helper type 1 (Th1) cells are considered important in atherosclerosis, the relationships between Th1 and Th2 cells and atherosclerosis have not been examined in population-based studies. METHODS AND RESULTS We measured Th cells as a percentage of lymphocytes by flow cytometry using CD4 staining (%CD4) in 917 participants of the Multi-Ethnic Study of Atherosclerosis. We also measured interferon gamma-positive and interleukin-4-positive CD4(+) cells, representing Th1 and Th2 subpopulations (%Th1 and %Th2), respectively. We found that %CD4 was 1.5% lower per 10 years of age (P<0.0001). Whites had higher %CD4 and lower %Th1 and %Th2 values than other race/ethnic groups. Body mass index (BMI) and blood pressure were associated with %CD4, but no traditional cardiovascular disease (CVD) risk factors were associated with %Th1 or %Th2. In multivariable models, the major independent variable associated with %Th1 was cytomegalovirus (CMV) antibody titer, with minor contributions from age, sex, seasonality, and interleukin-6. In models with coronary artery calcification level as the outcome, significant independent variables included age, sex, smoking status, and %Th1 (β=0.25; P ≤ 0.01). Both %Th1 and %Th2 were associated with common carotid intimal media thickness (β=0.02 and -0.02, respectively; both P<0.05), as were age, sex, race/ethnicity, blood pressure, and BMI. CONCLUSIONS Th1 bias is associated with subclinical atherosclerosis in a multiethnic population. The main Th1 correlate was CMV infectious burden. These findings are consistent with a role of Th1 cells in atherosclerosis and suggest the importance of prospective studies of T-helper cell biasing in CVD.