The distribution and relative immunogenicity of calf alpha-crystallin antigenic determinants on different subunits.

In the native alpha-crystallin molecule, 45.9% of all reactive antigenic determinants were found to be located on SH-containing subunits. Of these, the majority (35.3%) were reaggregation dependent, and 10.6% were reactive on monomeric subunits. By contrast, only 10.9% of all antigenic determinants were located on SH-free subunits, and the ratio of aggregation-dependent determinants (4.4%) to those of monomeric subunits (6.5%) was reversed compared to SH-containing subunits. Among all antigenic determinants reactive in native alpha-crystallin, 44.1% were dependent on the presence of both types of subunits. These data indicate that the antigenic determinants requiring subunit interaction were formed from SH-containing and SH-free subunits in a ratio of 1:1. Direct analysis showed that in the alpha-crystallin molecule, the ratio of these subunits is 2:1. The experiments indicate that some conformations of subunits in the native molecule persist in separated subunits. The relative immunogenicity of each type of antigenic determinant expressed as the ratio of the percentage of the determinant reactive in the native calf lens alpha-crystallin to the percentage of corresponding antibodies induced by native alpha-crystallin was found to be close to 1.