T lymphocyte abnormalities in juvenile systemic sclerosis patients

- jSSc patients have decreases in resting regulatory T lymphocytes.
- Decreased thymic function may contribute to the decrease in regulatory T lymphocytes.
- The frequency of CD45RA expressing effector memory CD4 T lymphocytes is increased.
- Patient leukocytes have increased CCR7 and CD22 gene expression.
- CD4 T lymphocytes have an increased frequency of CCR7 expressing cells.

Multi-center evaluations of pediatric patients with juvenile systemic sclerosis (jSSc) have suggested that the pathogenesis of jSSc may differ from that of systemic sclerosis (SSc) in adult patients. Therefore, we undertook to identify abnormalities in the T lymphocytes of jSSc patients and to determine if they differed from the abnormalities reported in the T lymphocytes of adult SSc patients. We identified decreases in the frequency of resting regulatory T lymphocytes and an increased frequency of CD45RA expressing effector memory (EMRA) CD4 T lymphocytes, which were characterized by an increased frequency of CCR7 protein expressing cells. Neither the increases in the EMRA subpopulation nor the increased CCR7 protein expression have been reported in adult SSc patients. The decrease in resting regulatory T lymphocytes in jSSc patients may permit the expansion of the disease initiating CD4 T lymphocytes present in the CCR7 expressing EMRA CD4 T lymphocyte subpopulation.