Separation of mouse homocytotropic antibodies by biological screening

Abstract

An attempt was made to separate mouse γ₁ antibody from mouse reaginic antibody by injecting mouse antiserum containing both antibodies into normal mice and then at 6 and 24 hours bleeding the animals and testing their sera for passive cutaneous anaphylaxis (PCA) activity. This was termed biological screening. The 2-hour homologous PCA activity was used as a measurement of mouse γ₁ and the rat PCA activity of the mouse antisera was used as a measurement of mouse reaginic antibody. These experiments showed that in vivo screening of mouse antisera containing both mouse and rat PCA activity results in removal of the rat PCA activity of these sera whereas the mouse PCA activity remains practically unchanged. It is concluded that a separation of the mouse serum PCA activity due to γ₁ antibody from that due to mouse reaginic antibody can be achieved by biological screening. Screening experiments using very early mouse antisera collected 8 days after a single antigenic stimulation resulted in the simultaneous disappearance of both homologous and heterologous PCA activity. Heating of these very early antisera resulted in complete inactivation of heterologous PCA activity and almost complete inactivation of homologous PCA activity. Absorption of these same antisera with rabbit anti-mouse γ₁ caused no change in homologous or heterologous PCA activity. It is suggested that the PCA activity of the very early antisera is due almost entirely to mouse reaginic antibody.