Loss of CD31 receptor in CD4+ and CD8+ T-cell subsets in children with primary hypertension is associated with hypertension severity and hypertensive target organ damage

BACKGROUND: Primary hypertension is associated with still poorly known T-cell dependent immunity defects that participate in the disease development. However, the relationship between peripheral T-cell subset distribution and disease severity in humans is not known. The aim of the study was to find out if target organ damage in adolescents with primary hypertension is associated with thymus-dependent lymphocytes renewal reflected by changes in the T-cell subset phenotype characteristics. METHODS: Using seven-color flow cytometry technique, we assessed CD31, CCR7 and CD28 receptors expression in CD45RA and CD45RO bearing peripheral CD4 and CD8 T-cell subsets. The study included 32 hypertensive children/adolescents and 35 sex-matched and age-matched controls. RESULTS: Children with primary hypertension had slightly increased CD4 T-cell pool but decreased population of CD31 expressing CD4 T-cell subsets (recent thymic emigrants). Frequency of the CD4 and CD4/CD45RA+ T cells lacking CD31 correlated positively with the hypertensive organ damage markers (pulse wave velocity, central blood pressure, left ventricular mass index). Left ventricular hypertrophy was associated with decreased CD4/CD45RA:CD4/CD45RO ratio, loss of the CD31 receptor in the CD4 and CD8 T-cell subsets and increased population of effector/memory T cells bearing CD8/CD28 and CD8/CD45RA+/CCR7 phenotype. Regression analysis revealed that these associations were independent of age, sex, and BMI. CONCLUSION: The results suggest that subclinical arterial injury and left ventricular hypertrophy in adolescents with primary hypertension is associated with declined thymic function and increased pool of T cells bearing effector/memory phenotype.