Immunologic Responses of Neonatally Thymectomized Rats to Sheep Red Blood Cells and to Flagellin from Salmonella adepaide 1

Abstract

Summary

Rats thymectomized at birth and immunized with sheep erythrocytes at 4 to 8 weeks of age showed cellular and serologic responses comparable with normal or sham-thymectomized rats. However, thymectomized rats immunized at 4 weeks of age with flagellin from S. adelaide showed a markedly impaired serologic response, while sham-thymectomized rats had high titers of immobilizing antibody in their sera. Despite the impaired serologic response to flagellin, thymectomized rats acquired nearly equal numbers of lymphoid cells with specificity for flagellin as measured by adherence to their surfaces of viable bacteria possessing flagellar antigens in common with the flagellin used for immunization. This work implies that neonatal thymectomy in this antigen system may interfere with the synthesis of specific antibody rather than antigen recognition following immunization. Although the origin and role of these lymphoid cells showing immunocytoadherence has not been clarified, these data may represent evidence for the antigen-stimulated proliferation of bone marrow-derived antibody-forming cell precursors in the absence of thymus-derived cells.