Effect of Multiple Injections of Antigen upon the Specificity of Antisera

Abstract

Rabbits were injected with small amounts of the hemocyanins of Crustacea for four or five short series. Three animals were presensitized with antigen, and then given several series of injections after a period of rest of thirty days. The change in the content of antibody, and the change in the specificity of the antisera were observed after each series by means of a photoelectric, turbidimetric titration of the entire range of reaction between antigen and antibody. The amount of antibody in the antisera generally increases following each series of injections. However, decreases have been observed to occur following the third and fourth series. The specificity of antisera generally decreased during the course of immunization. However, increases in specificity following previous decreases in specificity also occurred. Presensitization seems to be equivalent to one or two series of injections in so far as the specificities of antisera are concerned. Relatively large dilutions of immune sera which are in the “maximal antibody-constant specificity” state do not increase their specificity. The specificity of an antiserum is primarily dependent upon the physiological state of the animal which produces it. Under uniform schedules of injection the specificities of antisera produced against the same antigen will vary from animal to animal. Thus, the specificity of an antiserum is not necessarily correlated with the amount of antigen involved in the immunization. The specific characteristics of the antigens, which are being compared, help to determine the specificity which is ascribed to an antiserum.