Figure 5

Phagocytized L. monocytogenes, activated γδ T cells to induce CD4 cell and CD8 T cell proliferation. (A) PBMC, PBMC plus L. monocytogenes, PBMC plus γδ T cells or PBMC plus γδ T cells infected by L. monocytogenes were cultured for six days then the total cell number in each group was counted. L. monocytogenes alone did not promote PBMC proliferation. γδ T cells displayed a slight augment to PBMC proliferation at a high ratio of γδ T cells to PBMCs. However, the γδ T cells which phagocytized L. monocytogenes induced significant PBMC proliferation. The ratios of the numbers of proliferated (B) αβ T cells, (C) CD4⁺ T cells and (D) CD8⁺ T cells to initial PBMC numbers after six days incubation. A more significant proliferation was observed when γδ T cells were cultured at 1:1 ratio of γδ T cells to PBMCs. (E) αβ T cells were isolated from PBMC and cocultured with γδ T cells in the presence or absence of L. monocytogenes. γδ T cells could promote the proliferation of αβ T cells, especially after phagocytosed L. monocytogenes. The cell number, ratio and percentage are shown as mean ± SEM (independent experiment of n = 4). *P < 0.05. **P < 0.01. Ratios represent as the proportions of the final cell numbers after incubation over initial numbers of PBMCs.