A proteolytically truncated form of free CD18, the common chain of leukocyte integrins, as a novel marker of activated myeloid cells.
An unusual CD18 monoclonal antibody (mAb) MEM-148 binds, in contrast to standard CD18 mAbs, specifically to peripheral blood monocytes and neutrophils activated by various stimuli such as phorbol myristate acetate, opsonized zymosan, heat-aggregated immunoglobulin, and (after priming with lipopolysaccharide, tumor necrosis factor, or granulocyte-macrophage colony-stimulating factor) also by formyl-methionyl-leucyl-phenylalanine. In addition, in vivo activated neutrophils obtained from urine of patients following recent prostatectomy were also strongly positive for MEM-148. On the activated myeloid cells the mAb recognized a 65- to 70-kd protein identified immunochemically and by mass spectrometric peptide sequencing as a membrane-anchored fragment of CD18 (the common chain of leukocyte integrins) produced by proteolytic cleavage. The CD18 fragment originated mainly from integrin molecules stored intracellularly in resting cells, it was unassociated with CD11 chains, and its formation was inhibited by several types of protease inhibitors. Thus, the 65- to 70-kd CD18 fragment represents a novel abundant activation marker of myeloid cells of so far unknown function but possibly involved in conformational changes in leukocyte integrin molecules resulting in increased affinity to their ligands.
Drbal
K
K
Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Angelisová
P
P
Hilgert
I
I
Cerný
J
J
Novák
P
P
Horejsí
V
V
D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D015415:Biomarkers; D015153:Blotting, Western; D018821:CD18 Antigens / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002448:Cell Adhesion; D015180:Electrophoresis, Gel, Two-Dimensional; D010450:Endopeptidases / Q000378:metabolism; D000939:Epitopes / Q000032:analysis* / Q000276:immunology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D013058:Mass Spectrometry; D009000:Monocytes / Q000737:chemistry / Q000187:drug effects; D022423:Myeloid Cells / Q000737:chemistry* / Q000187:drug effects; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000737:chemistry / Q000187:drug effects; D010446:Peptide Fragments / Q000032:analysis* / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015054:Zymosan / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D015415:Biomarkers; D018821:CD18 Antigens; D000939:Epitopes; D007074:Immunoglobulin G; D008070:Lipopolysaccharides; D010446:Peptide Fragments; D014409:Tumor Necrosis Factor-alpha; D009240:N-Formylmethionine Leucyl-Phenylalanine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D015054:Zymosan; D010450:Endopeptidases; D013755:Tetradecanoylphorbol Acetate