MEC3 and MEC5 are auto-antibodies derived from DZB rats that had 
  developed membranous glomerulopathy upon exposure to mercuric chloride 
  (Aten et al. 1995).

  Both rat monoclonal antibodies are directed against the P1 fragment of laminin. 
  They are species-independent as it has been shown that they bind to laminin of rat, 
  mouse and humans (Aten et al., 1995).

  MEC3 and MEC5 monoclonal antibodies are especially useful for immunohistochemical 
  detection of laminin in extracellular matrix or basement membranes in freshly frozen 
  tissue sections of rat,  mouse or humans. For MEC5 it is recommended to pretreat the 
  sections with pepsin. 

  Aten J, Veninga A, Coers W, Sonnenberg A, Timpl R, Claessen N, Van Eendenburg JD, 
  de Heer E, Weening JJ (1995) Autoantibodies to the laminin P1 fragment in 
  HgCl2-induced membranous glomerulopathy. Am J Pathol 146: 1467-1480