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. 2015 Sep 14;10(9):e0138042. doi: 10.1371/journal.pone.0138042

Fig 3. Evaluation of the effect of freezing PBMC for storage on cytokine expression after in vitro stimulation for 5 days with Mtb antigens.

Fig 3

Comparison of total cytokine expression (IFNγ, TNFα and/or IL-2) of CD3+CD4+ T cells after stimulation of fresh or thawed cells with PPD (A), HBHA (B) and ESAT-6 (C). Open circles and filled squares represent uninfected controls and latent tuberculosis-infected (LTBI) subjects respectively. Horizontal lines represent median frequency of cytokine-expressing cells of controls (dotted) and LTBI subjects (full). (D) For 10 LTBI subjects, the frequency of cytokine-expressing cells is evaluated as single positive (white), double positive (grey) and triple positive (black) cells based on the combination of expressed cytokines (IFNγ, TNFα and IL-2) for fresh (F) and thawed (T) PBMC stimulated with HBHA. Statistical analysis was by Wilcoxon matched pairs signed rank test. * p<0.05, ** p<0.01.