Characterization of Early 19 S and Late 7 S Immunoglobulins in the Mouse

Abstract

Summary Biphasic responses and differing rates of neutralizing activity of early and late sera from BALB/Sy mice given single and multiple injections of actinophage indicated two types of antibodies in phage neutralization. By the use of physical and immunochemical techniques the neutralizing activity of early serum was found to be associated with a γ1-immunoglobulin of the 19 S class. The late serum contained mostly a γ2-immunoglobulin of the 7 S class. The early 19 S antibody was inactivated by 2-mercaptoethanol in contrast to the stability of the late 7 S γ2 antibodies. Immunoelectrophoretic patterns of pooled mouse sera were typical of rabbit and human patterns. In the mouse, however, mercaptoethanol dissociates the so-called β2M into a new component with the mobility of, but antigenically distinct from, the γ2-immunoglobulin. In the mouse, the 19 S immunoglobulin is not related to the classical β2M line but is associated with the fast γ2-globulin and appears antigenically identical. The implication of the apparent close relationship of these two classes of immunoglobulin is discussed in relation to the mechanism of their production.