RESUMEN
It has been previously established that an intravenous injection of a protein antigen solution into mice primed with the same antigen in the form of a protein-cellulose complex induces an intensive antibody production (up to 10,000 antibody-forming cells/10(6) splenocytes and up to 3 mg of antibodies/ml of serum). The present study has shown that secondary immune response can be considerably enhanced if large amounts of the antigen are administered intraperitoneally in a protein-cellulose complex during secondary immunization. In these experiments the mean number of antibody-forming cells was 50.000/10(6) splenocytes and the antibody serum level averaged 10 to 12 mg/ml. The effect persisted for a long time: as late as on day 80 the antibody concentration was 2 mg/ml of serum.