Abstract
1. Rabbits were immunized with both normal (Nrbc) and trypsinized (Trbc) human red blood cells and the antisera examined with normal, trypsinized, periodate-treated, and hemolytic anemia cells.
2. Absorption studies showed the presence of a fraction in both anti-Trbc and anti-Nrbc that was specific for trypsinized cells.
3. This T cell specific fraction from anti-Trbc serum (anti-TE) did not agglutinate or sensitize normal red blood cells, but agglutinated periodate-treated cells. This latter specificity was shown to be a part of the modification produced by trypsinization.
4. Anti-TE also agglutinated the cells of fifteen of nineteen patients with acquired hemolytic anemia and three of thirteen cases of hereditary spherocytosis.
5. Antibody for trypsinized and normal cells was also detected in antiserum to normal cells. Absorption data suggested the presence in this antiserum of antibody with a dual specificity for both types of cells.
6. The role of the antigenic modifications produced by trypsin in red cell immunization and in hemolytic anemia is discussed.
