CD8A and systemic lupus erythematosus: Phenotypic analysis of frequencies of perforin+ and granzyme B+ populations in peripheral blood in SLE has shown that CD8+ T cells exhibit an increased cytotoxic phenotype, in particular in active patients, as granzyme B+ and perforin+ populations were elevated in SLE compared to HC [30,63,70] and correlated positively with SLEDAI score [30,70].