Immunologic Unresponsiveness in the Adult Guinea Pig

Summary

The degree and persistence of immunologic unresponsiveness, induced in the adult guinea pig with a single intravenous injection of protein antigen in saline, depended on the time relationships between administration of the suppressing and sensitizing injections. Unresponsiveness was maximal when suppressing and sensitizing injections were administered concurrently. As the interval between the suppressing and sensitizing injections was increased, progressively less unresponsiveness resulted. Animals receiving a “suppressing” intravenous antigen injection 6–12 weeks prior to sensitization developed increased 7 S_γ1 antibody titers, suggesting that the suppressing injection was itself potentially immunogenic. It was also possible to induce immunologic unresponsiveness as late as 10 days after administration of a sensitizing injection of antigen, at a time when the animal already manifested a weak immune response; however, larger doses of suppressing antigen were required.

Delayed skin reactivity was most readily suppressed by intravenous antigen and last to recover. Hemolytic antibody production followed an intermediate course, while 7 S_γ1 antibody production was most resistant to suppression and the first to recover. The differences in suppressibility of these immune functions may reflect differences in the sensitivity of the techniques used to measure them or may indicate that these immune functions arise independently, possibly from different cell lines.