Figure 2.

Proliferation responses of pneumococcal surface adhesin A (PsaA) peptide-specific systemic and mucosal CD4⁺ T cells during pneumococcal carriage. Cervical lymph node (CLN) and splenic lymphocytes were isolated, 28 days after intranasal challenge, from both Streptococcus pneumoniae strain EF3030 challenged (▮), and naive (□) F₁ (B6 × BALB/c) group mice. CD4⁺ T cells were incubated with 1 μm of PsaA peptide (15-amino acid peptides that overlapped every 11 residues) plus mitomycin C-treated naive syngeneic feeder cells, for 3 days, at a ratio of 5 : 1 × 10⁶ cells. Proliferation was measured by 5-bromo-2′-deoxy uridine incorporation, which was measured by ELISA. The data presented are the mean optical density at 450 nm (OD₄₅₀). Experimental groups consisted of 10 mice. The results were expressed as mean ± standard error of mean (SEM) of the response from three replicates. (*) represents the peptides showing significantly higher proliferation response. Dotted line (–) represents the cut-off value above which the values were considered significant.