Differentiation between vascular permeability factor and IL-2 in lymphocyte supernatants from patients with minimal-change nephrotic syndrome.
Immunotherapy of cancers with recombinant IL-2 induces a vascular leak syndrome which is mainly due to an increase in vascular permeability. A lymphokine, the vascular permeability factor (VPF), which increases vascular permeability, has been characterized in minimal-change nephrotic syndrome (MCNS) and appeared very similar to IL-2. Here we have undertaken a further characterization of VPF in order to determine how closely related this factor was to human IL-2. Both the IL-2 bioassay and Western blot analysis of the MCNS lymphocyte concentrated supernatants with high VPF activity revealed the presence of low quantities of IL-2. Preparative isoelectrofocusing (IEF) of concentrated supernatants resolved each lymphokine in a separate peak, with apparent pIs of 5.2 for VPF and 7.5-10.1 for IL-2. Since a sensitive IL-2 ELISA failed to exhibit any significant antigenic presence of IL-2 in the IEF fractions with the highest VPF activity, we conclude that VPF activity of the concentrated supernatants is not related to IL-2 nor to a biologically inactive form of IL-2. When concentrated supernatants were subjected to preparative SDS-PAGE, VPF activity was recovered within low mol. wt material (1-12 kD). Immunoadsorption experiments gave definite proof since the complete removal of IL-2 from concentrated supernatants did not affect the VPF activity. Although high amounts of IL-2 increased vascular permeability, our experiments clearly demonstrate that VPF is a lymphokine distinct from IL-2.
Heslan
J M
JM
INSERM U 139, Hôpital Henri Mondor, Créteil, France.
Branellec
A I
AI
Pilatte
Y
Y
Lang
P
P
Lagrue
G
G
D000818:Animals; D001681:Biological Assay; D015153:Blotting, Western; D002199:Capillary Permeability; D016228:Endothelial Growth Factors / Q000737:chemistry*; D006168:Guinea Pigs; D006801:Humans; D007376:Interleukin-2 / Q000737:chemistry; D007526:Isoelectric Point; D008222:Lymphokines / Q000737:chemistry*; D008970:Molecular Weight; D009402:Nephrosis, Lipoid / Q000097:blood / Q000503:physiopathology*; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D007376:Interleukin-2; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors