Synthetic antigens composed exclusively of L- or D-amino acids. 3. Anamnestic response to a synthetic polypeptide composed exclusively of D-amino acids.

Several attempts were made to elicit an anamnestic antibody response in mice to 247, poly(D-Tyr, D-Glu, D-Ala), a synthetic polypeptide composed exclusively of D-amino acids. Although anamnestic responses have been repeatedly found with L-amino acid polypeptide antigens under a variety of conditions, they have not been found under similar conditions with D-amino acid polypeptides. Nevertheless, definite anamnestic responses to D-amino acid polypeptides can be evoked. A necessary condition is a long interval between primary and secondary immunization. Sufficient conditions for such a response were not established. The findings could be explained if antigen sensitive `memory' cells are generated by a primary immunization with D-amino acid polypeptides, but appear only late in the response. The possible reasons for this delay are discussed. The results are comparable to those found by others with pneumococcal polysaccharide antigens in mice.