Specificity of Cell-mediated Transplantation Reactions. I. STUDIES WITH THE TECHNIQUE OF INHIBITION OF MIGRATION AND AN ASSAY OF TUMOUR IMMUNITY <em>IN VIVO</em>.

The in vitro assay of inhibition of Ieucocyte migration was used in two forms for the study of the specificity of transplantation immunity in mice. In one system thymus cells (antigen) were mixed with peritoneal exudate cells (PEC) from mice immunized with skin grafts and inhibition of migration was detected only when the antigenic cells were of donor origin or were from a third-party strain which shared an H-2 region (K or D) with the graft donor. However, in another form of the assay, in which sensitized lymph node cells (LNC) were mixed with antigenic PEC, inhibition of migration was detected also using antigenic cells from third- party strains which did not share an H-2 region with the donor and possessed only few H-2 specificities of the donor, The inhibition of migration mediated by LNC was abrogated with the use of anti-θ sen. Transplantation immunity was studied in vivo with an assay of resistance to the growth of a third-party tumour (SaI) in mice pre-immunized with skin grafts from congenic strains having different H-2 antigens. Resistance was found in cases where the tumour cells did not share an H-2 region with the graft donor, but was weaker than the resistance obtained upon immunization with grafts from strains sharing an H-2 region with the tumour donor. [ABSTRACT FROM AUTHOR]