CTLA4 and microscopic polyangiitis: The PCA plot (Figure 2) distinguished the disease clusters: MPA, GPA, sarcoidosis and HC showed that they were separated on the basis of CD4+CTLA4+, CD4+PD1+, CD4+TIGIT+, CD56, CD56+CTLA4+, CD56+TIGIT+, CD8, CD8+CTLA4+ and CD8+PD1+.