A monoclonal antibody raised against human beta-factor XIIa which also recognizes alpha-factor XIIa but not factor XII or complexes of factor XIIa with C1 esterase inhibitor.
A monoclonal antibody (mAb 2/215) against human beta-factor XIIa (beta-FXIIa), was shown by equilibrium binding studies to have a high affinity for alpha-factor XIIa (alpha-FXIIa) (Kd 1.8 nM) and beta-FXIIa (Kd 0.65 nM) but no detectable reaction with FXII zymogen or alpha-FXIIa:C1 esterase inhibitor (C1-INH) complex. Surface plasmon resonance studies showed that the mAb 2/215 bound to immobilized alpha-FXIIa with high affinity (KD 3.93 +/- 1.46 x 10(-11) M). Western blots employing mAb 2/215 indicated that human plasma contained small amounts of alpha-FXIIa but no beta-FXIIa. mAb 2/215 did not inhibit the amidolytic activity of beta-FXIIa and protected beta-FXIIa from inhibition by C1-INH. The recovery by ELISA,employing mAb 2/215 as the capture antibody, of alpha-FXIIa added to plasma was 11.3%, 42% after inhibition of alpha-FXIIa with 3:4dichloroisocoumarin, and 82% when 0.5% Triton-X100 was added to the assay. Gel filtration showed that the majority of plasma alpha-FXIIa existed as a complex (Mr approximately 170,000). This distinctive mAb increases the capacity to study the contact system in health and disease.
Esnouf
M P
MP
Nuffield Department of Clinical Biochemistry, University of Oxford, The Radcliffe Infirmary, UK.
Burgess
A I
AI
Dodds
A W
AW
Sarphie
A F
AF
Miller
G J
GJ
D000581:Amidohydrolases / Q000187:drug effects / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D000918:Antibody Specificity; D015153:Blotting, Western; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D003174:Complement C1 Inactivator Proteins / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D005174:Factor XII / Q000276:immunology; D015956:Factor XIIa / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D011485:Protein Binding; D020349:Surface Plasmon Resonance
D000911:Antibodies, Monoclonal; D003174:Complement C1 Inactivator Proteins; D000939:Epitopes; D005174:Factor XII; D015956:Factor XIIa; D000581:Amidohydrolases