Production and characterisation of monoclonal antibodies specific for staphylococcal enterotoxin B.

We have generated monoclonal antibodies (MABs) to staphylococcal enterotoxin B (SEB) in BALB/c mice. Five out of 20 clones which produce anti-SEB MABs have been characterised. Among them, three produce IgG1/kappa, one produces IgM/lambda, and one apparently produces both IgG1/lambda and IgM/lambda MABs. The anti-SEB titres of ascites fluids range from 3200 to greater than 819200 by ELISA. All of the MABs analysed thus far neutralise the mitogenic response of BALB/c splenocytes to a suboptimal dose of SEB. Also, the induction of suppressor cells by SEB in vitro is reversed by pre-incubating SEB with these MABs. Limited digestion with chymotrypsin, trypsin or Staphylococcus aureus V8 protease yields peptide fragments which have been tested by Western-blot analysis. MABs 1FD7 and 2GD9 are specific for the carboxy-terminal end of SEB, and have a similar, but not identical, binding epitope. MABs 2DA3 and 2HA10 bind to intact SEB but not to cleaved products, and are probably specific for antigenic determinants altered by the cleavage or by the denaturing conditions of the electrophoresis, or by both.