Perforin gene expression in stimulated human peripheral blood T cells studied by in situ hybridization and northern blotting analysis.

In situ hybridization was used here to monitor the mRNA level of the pore-forming protein perforin in mitogen-stimulated primary peripheral blood human T cells. In situ hybridization was performed using sense and antisense ribonucleotide probes specific for this granule mediator. After IL-2 treatment, an increase in perforin mRNA could be detected by 4 h; they peaked at 12 h, and decreased after 24 h. The perforin mRNA was also induced in T cells treated with a combination of phorbol ester PMA plus lectin or OKT3 mAb. This latter induction followed slower kinetics, peaking at 48 h. For all three mitogens used, even at peak induction times less than 10% of T cells were labeled with perforin probe. Similar patterns of mRNA expression were observed for both unprimed T cells and lectin-primed T blasts. The induction response of mRNA due to IL-2 stimulation is probably mediated by the IL-2 receptor p75 chain since its mRNA was upregulated by IL-2 with a kinetics comparable to that associated with an increase of perforin mRNA. The p55 IL-2 receptor chain increased much more slowly than p75.