Immunogenic properties of modified antigen E. I. Presence of specific determinants for T cells in denatured antigen and polypeptide chains

Denaturation of antigen E in 8 M urea or by reduction carboxymethylation treatment resulted in loss of antigenic determinants in native molecules. The denatured antigen preparations, as well as the α and β polypeptide chains isolated from the antigen upon its dissociation, failed to combine with rabbit or human IgG antibody against the native antigen, or to induce erythema wheal reactions in ragweed sensitive individuals. The denatured antigens and the polypeptide chains, however, enhanced anti DNP antibody response of DNP ragweed (DNP Rag) primed rabbit lymph node cells to DNP keyhole limpet hemocyanin (KLH). When the primed lymph node cells were treated with DNP KLH for 24 hr, and then cultured in the presence of one of these modified antigens, both IgG and IgE anti DNP antibodies were formed in vitro. The activity of the modified antigens to stimulate carrier specific helper cells was comparable to that of native antigen. All of the modified antigens induced DNA synthesis of peripheral lymphocytes of ragweed sensitive patients but not the lymphocytes of normal individuals. The results indicated that denatured antigen E as well as α and β polypeptide chains possess determinants specific for T cell receptor.