Ripley-like anti-Rh associated with red blood cell-bound IgG aggregates

A commercial Rho (D) immune globulin after heating at 63 C became Ripley-like in the Rh-positive red blood cells coated with this heated globulin carried biologic activities similar to those of red blood cells coated with Ripley anti-CD serum. These coated red blood cells fixed complement and were agglutinated by all 20 sera containing rheumatoid factor (RF). The RF-Rh-hemagglutinations were more readily inhibited by heated than by unheated human IgG. The heated globulin had no such effect on Rh-negative red blood cells. Fractionation studies by Na2SO4 precipitation and/or Sephadex G-200 gel filtration revealed that heat-induced IgG aggregates in heated globulin were responsible for the biological activities. In contrast, these activities in Ripley serum were carried by IgG monomers. Another anti-CD serum (Heyman), tested in paralledl, was found to be indistinguishable from Ripley. a pooled RF serum, after multiple adsorptions with red blood cells coated with globulin, lost its agglutination activity to red blood cells coated with Ripley or Heyman serum.