CD8A and systemic sclerosis: The excessive proliferation of CD4+, CD8+, and double-negative (CD4–CD8–) T lymphocytes was observed in murine models of lupus and SLE patients (Tang et al., 2009; Balomenos et al., 2017; Du et al., 2019), while increased proliferation rate of naive and functionally differentiated CD4+ T cells was detected in SSc patients (Giovanetti et al., 2010).