Titration studies with IgG anti-A antibodies revealed similar activity at
both 4 and 37 °C. The saline activity of IgG anti-A antibodies generally increased as the
papain titre increased with both cord and adult A, and A2 cells. Sera with papain titres
>256 had saline titres in the range 32-256 at 37 °C.
Estimations of the IgG anti-A content of ‘immune’ anti-A sera made by titration
following partial neutralization revealed a decreasing quantitation of the results with
increasing saline IgG anti-A titre, as shown by comparison to the 2-ME method.