THE ROLE OF NF-KAPPA-B1 (P50 P105) GENE-EXPRESSION IN ACTIVATION OF HUMAN BLOOD T-LYMPHOCYTES VIA CD2 AND CD28 ADHESION MOLECULES/

Stimulation of primary human T-lymphocytes via CD2 and CD28 adhesion m olecules induces a long-lasting proliferation (>3 weeks). This potent activation does not require accessory cells, such as monocytes, but de pends on persistent interleukin 2 (IL-2) secretion and receptivity, wh ich is associated with high and prolonged expression of the inducible CD25/IL-2 receptor alpha (IL-2R alpha) chain gene. The transcription f actor NF-kappa B participates in the regulation of both IL-2 and IL-2R alpha genes, as well as multiple cellular genes involved in T-cell pr oliferation. To evaluate the role of NF-kappa B in human peripheral bl ood T-lymphocytes, we previously analyzed the activation of NF-kappa B -related complexes in response to CD2+CD28 costimulation. We demonstra ted a long-term induction of p50/p65 heterodimer, a putative p65/c-Rel heterodimer, and a constitutive nuclear expression of KBF1/p50 homodi mers. As the role of p50 remains unclear, we focused our present study on NF-kappa B1 (p50/p105) gene regulation. Using electrophoretic mobi lity shift assays and Western and Northern blot analyses, we studied N F-kappa B1 gene expression during T-cell stimulation via CD2+CD28. We observed a transient 4- to 5-fold increase of NF-kappa B1 gene express ion at both the mRNA and protein levels, lasting for at least 24 h. p5 0 DNA-binding activity apparently stays highly controlled when p105 ex pression is enhanced by a physiological stimulus of peripheral blood T -cells. Partial inhibition of p50 and p105 expression by NF-kappa B1 a ntisense oligonucleotides significantly reduced T-cell proliferation a rid CD25/IL-2R alpha cell surface expression. These data provide direc t evidence for a role of NF-kappa B1 gene positive regulation during C D2+CD28 stimulation of primary human T-cells.