Modification of surface membrane antigens by trypsin.

SummaryCultured 3T3 and PY-3T3 mouse fibroblasts were subjected to mild treatment with twice crystallized trypsin and their immunogenicity tested in ICR/ CD-1 mice. Surface antigenic modifications were observed using the foot pad swelling assay for detection of delayed hypersensitive responses. Mice immunized with trypsin-treated 3T3 cells showed cell-mediated immune reactions following challenge with either homologous antigen or untreated PY-3T3 fibroblasts. In contrast, treatment of the virus-transformed cells with trypsin decreased their antigenicity as determined by this in vivo assay.