Protein electrophoresis pattern

[Ctro Inmunologia Molecular]

   I am obtaining different electrophoresis pattern for a monoclonal 
 
   antibody in SDS- PAGE when I run gels in conventional system and 
 
   stain with coomasie ( Phast Gel Blue from pharmacia ) and when I run 
 
   PhastSystem gel stainig with Silver.the problem is that I obtain 
 
   several bands in conventional system and just one band with 
 
   PhastSystem, also I obtain a normal pattern for this monoclonal 
 
   antibody by IEF and NATIVE- PAGE with PhastSystem.
 
   
 
   What happen?
 
   Where those extrabands come from?
 
   If this extrabands are not artifacts Why I can not detect this band 
 
   by silver stain in phastSystem. 
 
   
 
   Advices and sugestions will be welcome.
 
   
 
   Thanks in advance.
 
   Ernesto
 
   monoclon at infomed.sld.cu