Epitope mapping of 10 monoclonal antibodies against the pig analogue of human membrane cofactor protein (MCP).
Pig membrane cofactor protein (MCP; CD46) is a 50 000-60 000 MW glycoprotein that is expressed on a wide variety of cells, including erythrocytes. Pig MCP has cofactor activity for factor I-mediated cleavage of C3b and is an efficient regulator of the classical and alternative pathway of human and pig complement. A panel of 10 monoclonal antibodies (mAbs) was collected from two different laboratories; all of these mAbs were raised against pig leucocytes and all recognized the same complex banding pattern on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of erythrocyte membranes. All were shown to be reactive with pig MCP and were divided into four groups of mutually competitive antibodies based on competition studies for membrane-bound MCP and for soluble MCP, the latter by surface plasmon resonance (SPR) analysis. The antigenic properties of membrane-bound and soluble MCP were similar, although some interesting differences were revealed. None of the 10 mAbs were cross-reactive with human MCP and only one showed cross-reactivity with leucocytes from a panel of large mammals - a weak cross-reactivity with a subset of dog leucocytes. All antibodies in one of the epitope groups and some in a second epitope group were able to block the functional activity of pig MCP, as measured by inhibition of MCP-catalysed C3 degradation by factor I.
Pérez De La Lastra
J M
JM
Department of Medical Biochemistry, University of Wales, College of Medicine, Cardiff, Wales, UK.
Van Den Berg
C W
CW
Bullido
R
R
Almazán
F
F
Domínguez
J
J
Llanes
D
D
Morgan
B P
BP
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D015703:Antigens, CD / Q000276:immunology*; D001667:Binding, Competitive; D003169:Complement Inactivator Proteins / Q000276:immunology*; D003429:Cross Reactions; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D018604:Epitope Mapping; D006801:Humans; D007962:Leukocytes / Q000276:immunology; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000276:immunology*; D013045:Species Specificity; D020349:Surface Plasmon Resonance; D013552:Swine / Q000276:immunology*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C497857:CD46 protein, human; D003169:Complement Inactivator Proteins; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins