Enhancement by Monocytes of Perform Production and Its Gene Expression by Human CD8+ T Cells Stimulated with Interleukin‐2

Pore‐forming protein (PFP) is an important effector molecule for cytotoxicity mediated by cytotoxic T cells and NK cells. In the present study, the effect of monocytes on PFP production by inter‐leukin‐2 (IL‐2)‐stimulated T lymphocytes was examined. Highly purified lymphocytes (>99%) and monocytes (> 90%) were isolated by centrifugal elutriation from peripheral blood of healthy donors, and, CD4+ and CD8+ cells were isolated from the purified lymphocytes by using antibody‐bound magnetic beads. PFP production was quantitated with a universal microspectrophotometer in combination with immunostaining using anti‐PFP antibody. Monocytes did not produce any PFP. High levels of PFP production were observed in CD8+ cells, but not CD4+ cells after incubation for 4 days with IL‐2. Addition of monocytes to cultures of CD8 + cells resulted in significant augmentation of PFP production after 3 days’ stimulation with IL‐2. Monokines (TNFα and IL‐6) caused a significant increase in PFP production by IL‐2‐stimulated CD8+ cells. Northern blot analysis revealed that the PFP mRNA level was enhanced by stimulation with IL‐2, and that addition of monocytes to cultures of CD8 + cells plus IL‐2 augmented their PFP mRNA expression. These observations suggest that monocytes are important in in situ regulation of the CD8 + T cell‐mediated cytotoxic response through production of PFP.