COMPARISON OF THE ABILITIES OF MHC-COMPATIBLE BONE-MARROW CELLS AND LYMPH-NODE CELLS TO INDUCE TOLERANCE OF SKIN ALLOGRAFTS IN RATS

A comparison has been made of the abilities of bone marrow cells and l ymph node cells to induce tolerance of skin when inoculated into neona tal rats known to differ only with regard to non-MHC incompatibilities , including putative skin-specific (Skn) antigens. Each recipient rece ived 50 x 10(6) cells, and tolerance was confirmed by the permanent ac ceptance of donor-strain neonatal heart tissue transplanted to the pin na of the ear. In 5 of the 8 MHC-compatible strain combinations tested , BMC were significantly more effective than LNC in inducing tolerance of skin, whereas in one situation LNC proved more efficient. Although the results are in accord with the occurrence of Skn antigens in rats , it appears that at least some of the antigens involved must also be expressed by BMC or LNC, but not equally by both of these tissues. The results also provide evidence that in rats, as in mice, the MHC can p lay a major role in determining the response to, and/or the immunogeni city of, Skn antigens.