Isolation of a granulocyte inhibitory protein from uraemic patients with homology of beta 2-microglobulin.
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).
Haag-Weber
M
M
Department of Medicine, University of Vienna, Austria.
Mai
B
B
Hörl
W H
WH
D000595:Amino Acid Sequence; D001798:Blood Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D006098:Granulocytes / Q000187:drug effects*; D006801:Humans; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014511:Uremia / Q000097:blood*; D001613:beta 2-Microglobulin / Q000302:isolation & purification*
D001798:Blood Proteins; D001613:beta 2-Microglobulin