Association of CD57⁺/CD27^– CD4⁺ T cells with lower TCR diversity and decreased MHC class II-expressing APCs. (A-D) Correlation between fraction of CD57⁺/CD27^– T cells and TCR and BCR diversity. Twenty-one patient samples with known fraction of CD57⁺/CD27^– T cells had TCR and BCR sequencing performed on bulk T and B cells. Diversity (inverse Simpson) indices expressed on a log axis for T and B cells are plotted with respect to the fraction of CD57⁺/CD27^– CD4⁺ T cells as well as CD57⁺/CD27^– CD8⁺ T cells. There is a negative association between the fraction of CD57⁺/CD27^– CD4⁺ (r_s = −0.88, P < .00001, expressed on a log axis) and CD8⁺ T cells (r_s = −0.65, P = .0014) with (A-B) TCR diversity but not with (C-D) BCR diversity. (E-L) Composition of PBMCs. For each cell type shown, the proportion of the cell type of total CD45⁺ PBMCs is plotted against the fraction CD4⁺ T cells that exhibit the CD57⁺/CD27^– phenotype. Cell populations that had a significant correlation to the phenotype included (H) classical monocytes (r_s = −0.41, P < .0001), (K) myeloid dendritic cells (r_s = −0.25, P = .024), and (L) plasmacytoid dendritic cells (r_s = −0.34, P = .0014).