O. Mühlbock

Histocompatibility genes (theH-2 complex) and susceptibility to spontaneous lung tumors in mice

The incidence of spontaneous lung tumors in relation toH-2, the major histocompatibility complex, was studied in congenic strains of mice on the B10-, A-, and C3H-backgrounds.The most relevant results were obtained with congenic strains on the B10-background. The strains could be divided into two groups: one with a low frequency of spontaneous lung tumors carrying the haplotypesH-2b,H-2h4,H-2d,H-2iH-2r and one with a higher incidence of lung tumors carrying the haplotypesH-2f,H-2m,H-2h2,H-2a. The differences between these two groups were highly significant.Analysis of the results obtained with the recombinant strains indicated that genes in theIB region determined the susceptibility to the development of spontaneous lung tumors.The comparison of the results in the B10, B10.A and A strain has shown that the incidence in the B10.A strain carrying the haplotypeH-2a derived from the highly susceptible strain A (H-2a) on the resistant background strain B10 (H-2b) is intermediate between these two strains. This shows, that other genes of the background are also involved.The lung tumor incidence in (B10.A × B10)F1 hybrids was intermediate between the two parental strains.The results obtained in the strains C3H with the haplotypeH-2k, C3H.B10 with the haplotypeH-2b and C3H.NB with the haplotypeH-2p, were inconclusive because of the early mortality which occurred among the animals of these strains. The strains A (H-2a) and A.SW (H-H-2s) were both equally susceptible.

The Mammary Tumor Agent in Completely Mammectomized Mice.

Summary Mammectomized female mice of the mammary tumor susceptible hybrid (♀ C3Hf × ♂ 020) group retained or propagated the mammary tumor agent. Two groups of agent-free recipients of splenic tissue from either mammectomized or intact donors that had been previously exposed to mammary tumor agent had a high incidence of mammary cancers at comparable ages. Controls not receiving splenic tissue failed to show mammary tumors.

Mouse Mammary Carcinoma Induced by Pituitary Isografts in Mammary Fat Pads

Summary Although in short-term experiments pituitary isografts have shown a direct local effect on the growth of the mammary gland, isografts of a hypophysis into the fat pads of the mammary glands showed no local effect on the incidence or an earlier appearance of mammary tumors near the site of implantation. The hormonal inciting influence is assumed to be so great that a local effect cannot be recognized. After isografting of hypophysis, a remarkable shift in the localization of the mammary tumors occurs: more tumors develop in the fourth and fifth pairs of glands than in untreated animals.