PCA reactions with mouse antibodies in mice and rats.

Mouse IgE was titrated in rats. The sensitization period was 2 h. The results were consistent and corresponded to the titers obtained in young adults SJL mice using a sensitization period of 48 h. With longer sensitization periods in rats, higher antibody titers were obtained. The optimum sensitization period in rats was found to be 48 h. Old CFW mice are inadequate for mouse IgE titration. IgG1 will not give a PCA reaction in rats. IgG1 titers are higher in SJL or A/J mice than in young CFW mice, and markedly higher than in old CFW mice.