Conformational studies of rat monoclonal immunoglobulin E

Two monoclonal IgEs (IR 2 and IR 162) were studied in terms of their conformational features by circular dichroism and differential u.v. absorption. The studies were performed both on the native proteins and under different conditions known to affect the biological properties of IgE (heating at 56 degrees C, acid pH, and presence of reducing agents). Whereas IgE IR 162 appeared to undergo significant conformational changes upon heating and at acid pH, IgE IR 2 was found to be unaffected or less affected by these treatments. The two monoclonal IgEs were found to be equally effective in blocking passive sensitization by IgE antibodies. However, the blocking capacity of IgE IR 162 was affected much more by heating at 56 degrees C than that of IgE IR 2.