Comparison of methods for the generation of immunoreactive fragments of a monoclonal antibody (B72.3) reactive with human carcinomas

J Immunol Methods. 1989 Jun 2;120(1):71-83. doi: 10.1016/0022-1759(89)90291-3.


Immunoglobulin fragments, whether of polyclonal or monoclonal antibodies, offer a number of advantages over the intact immunoglobulin. The generation of immunoreactive fragments from monoclonal antibodies (MAb) is not always a straightforward task. Both pepsin and papain can be used to digest MAb to a bivalent molecule with a Mr of 100,000. However, pepsin pepsin digestions does not always result in immunoreactive fragments and a stable consistent product by papain digestion is often difficult to obtain. MAb B72.3 is an example of both situations. MAb B72.3 reacts with a glycoprotein (TAG-72) with a molecular weight greater than 10(6). MAb B72.3 has been shown to exhibit a high degree of selective reactivity with colon, breast and ovarian carcinomas and has been used for radioimmunodiagnosis in model systems and in clinical trials. A third enzyme, bromelain, in the same family of sulfhydryl proteases as papain, has been used to generate a fragment of MAb B72.3, with a Mr of approximately 100,000. The bromelain-generated fragment of MAb B72.3 retained 100% immunoreactivity as measured in competitive solid-phase radioimmunoassays and could be generated with consistent results from one preparation to another. Both the bromelain- and papain-generated fragments were radiolabelled with 125I without significant loss of the MAb's reactivity to tumor extracts. Differences were observed between the bromelain- and papain-generated fragment when compared in vivo. Fragmentation of MAb B72.3 with bromelain has yielded a superior bivalent fragment for radioimmunolocalization.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / immunology*
  • Antibodies, Monoclonal / pharmacokinetics
  • Antibodies, Monoclonal / therapeutic use
  • Antibodies, Neoplasm / immunology*
  • Antibodies, Neoplasm / pharmacokinetics
  • Bromelains
  • Cell Line
  • Immunoglobulin Fragments / immunology*
  • Immunoglobulin Fragments / isolation & purification
  • Immunotherapy
  • Mice
  • Mice, Nude
  • Molecular Weight
  • Neoplasms, Experimental / diagnostic imaging
  • Neoplasms, Experimental / therapy
  • Papain
  • Pepsin A
  • Radionuclide Imaging


  • Antibodies, Monoclonal
  • Antibodies, Neoplasm
  • Immunoglobulin Fragments
  • Bromelains
  • Papain
  • Pepsin A