Figure 4

Inhibition of PD-1/PD-L pathway helped to control BCG replications when MDMs co-cultured with CD4⁺ T cells in vitro.

(A) Representative BCG CFU counts with different treatments. MDMs were infected with BCG (MOI = 10) for 4 h and then co-cultured with CD4⁺ T cells (MDMs/CD4 = 1:10) for 7 d. Whole-cell lysate was diluted and aliquots of each dilution of lysate were plated onto 7H11 agar and incubated for 3 wk at 37 °C until colonies were large enough to be counted. MDMs were prepared with the presence or absence of anti-PD-L1 and anti-PD-L2 Abs for 1 h before infection and CD4⁺ T cells were prepared with the presence or absence of anti-PD-1 Ab for 1 h before co-culture. (B) CD4⁺ T cells blocked with PD-1 Ab significantly inhibited the intracellular BCG replication in MDMs (P = 0.0263). Additionally, MDMs blocked with PD-L1/L2 Abs significantly inhibited the intracellular BCG replications (P = 0.0104). Blocking CD4⁺ T cells with PD-1 Ab and MDMs with PD-L1/L2 Abs similarly inhibited BCG replications in MDMs (P = 0.0264).