- Grafts of the metastatic 3LL Lewis lung carcinoma result in pulmonary metastases in mouse strains which share with the tumor strain of origin (C57BL/6, H-2b) the non-H-2 background genes and the H-2D/H-2L region of the major histocompatibility complex. Lung metastases across H-2K region disparities correlated with low expression of H-2Kb-encoded molecule on the tumor cell surface. We tested whether the 3LL tumor cells lack H-2Kb private and/or public specificities by staining 3LL tumor cells and spleen cells of different recombinant mouse strains with H-2d anti-H-2b and anti-3LL antisera, respectively, following absorption of the antisera on spleen cells from various recombinant mouse strains. The data demonstrated weak expression of H-2Kb public specificities (which could represent H-2Db/H-2Kb biregional encoded molecules) and a complete lack of expression of the H-2.33 H-2Kb private specificity by 3LL tumor cells. The findings provide a possible explanation for the 3LL metastatic potential across H-2Kb region disparities.