Studies on Synergistic Thymus–Bone Marrow Cell Interactions in Immunological Responses 1

Abstract

Summary and Conclusions

1. Marrow cells and thymus cells which had been exposed in vivo to SRBC antigen interact synergistically to produce hemolysin plaque-forming cells (Table II) (2).

2. The possibility of similar thymus-marrow cell interaction in producing cell mediated responses was tested in a variety of systems.

3. Synergistic interactions were not observed: (a) in the restoration of homograft reactivity of sublethally irradiated mice (Fig. 1); (b) in the production of graft-vs.-host responses as measured by splenomegaly (Figs. 3, 4, and 5) or of secondary disease (Table III) (cf. 4); and (c) in the restoration of the homograft response in sublethally irradiated, thymectomized recipients injected with marrow cells and with spleen cells from irradiated mice which had been injected previously with thymus cells and “weak” isoantigen (non-H-2).

4. A nonspecific stimulation of the homograft response occurred under conditions similar to 3c above but where the isoantigenic disparity was strong.

5. This nonspecific stimulation and the resuits of Globerson (9) which show a synergism between thymus and marrow cells in the production of in vitro GVH responses, offer perhaps the only known evidence that thymus–marrow cell interactions are involved in cell-mediated immunological responses.

6. Specific syngergistic interactions so evident in the initiation of the hemolysin response do not occur when cell-mediated immunological responses are tested under similar conditions. This does not definitely rule out the possibility that thymus–marrow cell interactions are involved in cell-mediated immunological responses.

7. Under certain conditions, thymus and bone marrow cell populations, like lymph node cell populations are each capable of conferring cell-mediated immunological competence. Hence these cell populations may have either one cell type capable of responding to isoantigen, or two or more cell types which interact to produce the response.