Fig 3.

Correlation of responses in PBMC frozen at two independent laboratories. Long-term cryopreserved PBMC (621–917 days frozen) from six individuals from the chronic HIV cohort (SCOPE) from the same phlebotomy processed at BSRI or at UCSF ASB were stimulated with SEB, HIV peptides, p55 protein or MN. CD4⁺ IFN-γ (a) and CD8⁺ IFN-γ (b) T cell responses were measured by three-color flow cytometry. Two-tailed, paired t tests were performed, and Spearman’s rank correlation coefficient (Rho) was calculated for BSRI processed versus ASB processed PBMC.