| Abstract: | A detailed evaluation of the capacity of mono-ε-DNP-oligo-L-lysines to initiate anti-DNP antibody synthesis and a state of delayed hypersensitivity in guinea-pigs is presented. Peptides containing as few as two lysine residues elicit the production of significant amounts of anti-DNP antibody when they are administered as Freund''s complete adjuvant emulsions. Under these immunization conditions, the serum concentration of anti-DNP antibody is dependent on the chain length of the peptide, and on the amount and kind of mycobacteria in the adjuvant; guinea-pigs lacking the PLL gene produce amounts of anti-DNP antibody indistinguishable from that produced by guinea-pigs possessing this gene. On the other hand, when guinea-pigs are immunized with either 1-ε-DNP-tetra-L-lysine or 1-ε-DNP-nona-L-lysine without the use of mycobacterial adjuvant, anti-DNP antibody is produced only by guinea-pigs receiving the nona-L-lysine and only by those animals possessing the PLL gene.Delayed hypersensitivity results from immunizing PLL+ guinea-pigs with mono-ε-DNP-octa and nona-lysines but not from immunization with mono-ε-DNP-hexa-lysine; PLL— animals do not exhibit delayed hypersensitivity to any of these compounds.The data suggest that antibody synthesis to positively charged compounds may proceed as a result of formation of charge complexes with mycobacterial proteins; under such immunization conditions the intrinsic immunogenicity of a compound is more reliably revealed by the induction or elicitation of cellular immune responses. On this basis, a definite discontinuity in the degree of immunogenicity of the mono-ε-DNP-oligo-L-lysines occurs as the peptides are lengthened from six to eight residues. |
