KLRB1 and systemic lupus erythematosus: The frequencies of Th17 cells, defined as CD4+CD161+CCR6+ IL17+IFN-γ−, were significantly decreased in pAPS patients, and also in HC, compared to SLE patients (p = 0.001 and p = 0.005, respectively), although no differences were found between APS vs. HC (Figure 2A).