R. Bos et al., A MONOCLONAL-ANTIBODY WITH HIGH-AFFINITY FOR A NEO-ANTIGENIC SITE IN FIBRINOGEN DEGRADED BY POLYMORPHONUCLEAR LEUKOCYTE-DERIVED ELASTASE, Blood coagulation & fibrinolysis, 6(3), 1995, pp. 259-267
Elastase, released by stimulated polymorphonuclear leukocytes (PMN), i
s thought to play an important role in the pathogenesis of chronic obs
tructive pulmonary disease (COPD) especially pulmonary emphysema. A te
st that can detect release of elastase activity from PMN would be valu
able to monitor therapy or to identify patients at risk. The authors a
imed to isolate and characterize monoclonal antibodies (mAb) with a hi
gh affinity for a neo-antigenic determinant in a high-molecular weight
degradation product of fibrinogen (Fbg) generated by PMN-derived elas
tase. Using synthetic peptides, they mimicked the new amino or carboxy
terminal sequences of the A alpha-, B beta- and gamma-chains of Fbg t
hat are generated by elastase. These synthetic peptides (A alpha 22-36
, A alpha 350-360, B beta 44-55, and gamma 295-305), uni-directionally
coupled to a carrier protein, were used to generate mAb specific for
elastase-degraded fibrinogen (EDF). mAb that appeared to be specific f
or a neo-antigenic determinant (neotope) consisting of the new amino t
erminal amino acid(s) of the Fbg A alpha-chain that is generated by el
astase activity were isolated only with the A alpha 22-36 synthetic pe
ptide. One mAb, designated as EF1-4, was further characterized and had
an approximately 75-fold higher affinity for EDF, as compared with Fb
g, in solution. Using the other peptides, no mAb specific for elastase
generated fibrinogen degradation products were obtained. Incubation o
f immobilized fibrin(ogen) with stimulated PMN resulted in the generat
ion of this specific neotope recognized by mAb EF1-4; the protease inh
ibitors alpha(1)-proteinase inhibitor (alpha(1)-PI) and antileukoprote
ase (ALP) decreased the generation by PMN of this neotope on Fbg. Fibr
inogen degradation products generated by plasmin or by other leukocyte
proteases, i.e. cathepsin G and proteinase 3, did not react with mAb
EF1-4.