CD8A and primary biliary cholangitis: The second, Metacluster-4 (Fig. 3B) expresses markers consistent with a subset of CD8+ T cells that express CD161 and PD1 (CD3+CD8+CD161+PD1+) and was found to be 2.7-fold lower in abundance in PBC patients relative to controls (0.6% vs. 1.6%; p < 0.001).