Isoform of vascular endothelial cell growth inhibitor (VEGI72-251) increases interleukin-2 production by activation of T lymphocytes.

The objective of this study is to investigate the characteristics of the recombinant variant of human vascular endothelial cell growth inhibitor, VEGI72-251, and compare its biological activities with that of its prototype VEGI24-174. The recombinant plasmid containing the variant VEGI72-251 gene was constructed and expressed in Escherichia coli. The effects of the expressed VEGI72-251 on cell proliferations were checked in the human umbilical vein endothelial cell line and certain tumor cell lines (ECV304 and B16). The inhibition of VEGI72-251 on angiogenesis was detected in the chorioallantoic membrane of chick embryos. In comparison with VEGI24-174, the recombinant human VEGI72-251 seems to have no effect on the proliferation of endothelial cells and the angiogenesis of the chorioallantoic membrane in vitro. An enzyme-linked immunosorbent assay-based method was used for the measurement of interleukin-2 (IL-2) production by peripheral blood monocytes (PBMCs) treated with VEGI72-251. PBMCs were pretreated with VEGI72-251 (1.25-12.50 microg/ml) for 24 h in vitro, and the IL-2 concentration in PBMC medium was increased from 354 pg/ml to 1256 pg/ml. It can be concluded that VEGI72-251 is able to increase the level of human IL-2 production by the activation of T lymphocytes. Differing from VEGI24-174 on anti-angiogenesis, VEGI72-251 may serve as an anti-cancer factor through its activation of T lymphocytes.