The capacity of fresh murine allogeneic bone to induce a specific immune
response in vitro was studied. T-cells stimulated by allogeneic bone in
vitro were collected and were characterized for state of activation,
cell-surface phenotype, and antigen specificity. The stimulating antigens
were determined by genetic mapping with use of recombinant inbred strains
of mice and by blocking of mixed lymphocyte cultures with use of
neutralizing antibodies. Purified T-cells were cultured alone or with
allogeneic or syngeneic bone. In some experiments, the bone marrow was
removed before in vitro culture. Responding cells were recovered after a
secondary exposure to the stimulating bone. Primed cells were used
immediately or cell-lines were developed. The data demonstrated that (1)
allogeneic bone activated T-cells and induced their proliferation; (2)
bone-induced proliferation of T-cells was specific for antigens that map to
the major histocompatibility complex of the bone donor; (3) within the
major histocompatibility complex, the antigens responsible for
proliferation of T-cells were apparently class-I and class-II determinants;
(4) removal of bone-marrow cells had no effect on the ability of that bone
to stimulate alloreactivity; and (5) all of the alloreactive T-cells had
the cell-surface phenotype Thy-+ CD8+ CD4-.