Isolation of a granulocyte inhibitory protein from uraemic patients with homology of beta 2-microglobulin

Nephrol Dial Transplant. 1994;9(4):382-8.

Abstract

Increased incidence of infection in uraemic patients is mainly caused by granulocyte dysfunction. Recently we discovered a granulocyte inhibitory protein (GIP I) in the ultrafiltrate of haemodialysis patients, that inhibits four fundamental functions of polymorphonuclear leukocytes (PMNLs). We now report on the isolation of a further polypeptide in end-stage renal disease patient ultrafiltrate using a polyamide filter with biological activity inhibiting healthy PMNL function in vitro. This protein (GIP II) has a molecular weight of about 9500 Da. In-vitro nanomolar concentrations inhibit PMNL O2- production and glucose uptake stimulated by phorbol-myristate-acetate (PMA), but not by formyl-methionyl-leucyl-phenylalanine (FMLP). In-vitro studies were performed to compare the effects of GIP I and GIP II on several PMNL functions. In contrast to GIP II, GIP I inhibits only FMLP-, but not PMA-stimulated PMNL glucose uptake. The NH2 terminal amino acid sequence (21 amino acids) of GIP II shows homology to beta 2-microglobulin. Commercially available intact beta 2-microglobulin had no effect on PMNL glucose uptake and O2- production. The beta 2-microglobulin homologue protein isolated from plasma ultrafiltrates of uraemic patients cross-reacts with three different commercially available assays for intact beta 2-microglobulin. Therefore, beta 2-microglobulin levels measured in the plasma ultrafiltrates of regular haemodialysis patients are overestimated with contribution of an uncertain amount of the beta 2-microglobulin homologue protein (GIP II).

MeSH terms

  • Amino Acid Sequence
  • Blood Proteins / isolation & purification*
  • Blood Proteins / pharmacology
  • Granulocytes / drug effects*
  • Humans
  • Molecular Sequence Data
  • Neutrophils / drug effects
  • Neutrophils / metabolism
  • Sequence Homology, Amino Acid
  • Uremia / blood*
  • beta 2-Microglobulin / isolation & purification*

Substances

  • Blood Proteins
  • beta 2-Microglobulin