PCA of cellular parameters determined by flow cytometry. (A) Plot of the eigenvalues that reflect the variance of the principal components when PCA is applied to all 36 cellular parameters with values from all 20 HIV-infected persons; 27.36% of the variance in this matrix of cellular parameters is contained in the first 2 principal components. (B) Each dot represents an HIV-infected person plotted in 2 dimensions using their projections onto the first 2 principal components. (C) The factors loading on the eigenvalues for PC1 reflect the amount of variance shared by the parameter with the PC1 values. Vertical brackets indicate the cellular parameters that are most notable for either their positive or negative association with the PC1 values.