Transplantation behavior of A.TH and A.TL T-cell lymphomas in congenic resistant and hybrid strains

Rous sarcoma virus-induced tumours in mice. II. Contribution of H-2 and non-H-2 alloantigen barriers to tumour immunogenicity in vivo

The features of the immune recognition of a murine fibrosarcoma induced by Rous sarcoma virus were tested in histocompatible and histoincompatible mice. No evidence of a genetic regulation of spontaneous reactivity to tumour-associated antigens was found in various histocompatible F1 hybrids. Incompatibility in multiple minor histocompatibility antigens triggers a host reaction incapable of causing tumour rejection in some cases. The growth rate of incipient tumours is unaffected, whereas that of already visible tumour masses is significantly delayed. Admixture to the challenge of inactivated leukocytes bearing the same minor histocompatibility antigens as the tumour triggers a significantly stronger reaction. The reaction of hosts incompatible in the H-2K or H-2DL regions is quite efficient. However, the intensity of the immune reaction of H-2DLs antigens displayed by tumour cells is markedly dependent on the alleles of genes located in the central regions of the H-2 complex.

Tumor progression in metastasis: an experimental approach using lectin resistant tumor variants

A novel model of tumor progression in metastatic cancer is described which grew out of attempts to derive stable non-metastatic variants from a highly metastatic mouse tumor called MDAY-D2. The variants were obtained by selection of so-called lectin-resistant (LecR) membrane mutants using toxic concentrations of wheat germ agglutinin (WGA) as the selective agent, after mutagenesis. Cloned WGAR variants almost all appeared to be highly tumorigenic and metastatic, but displayed altered growth properties which were highly suggestive of major cellular phenotypic alterations occurring prior to metastasis. This were confirmed with the discovery that spontaneous visceral metastases always consisted of WGA-sensitive (WGAS) 'revertant' tumor cells. Such revertants also arose at the site of the subcutaneous inoculation and, with time, comprised an increasing proportion of the tumor cells at that location. The WGAS/high metastatic phenotype was stable in vitro or in vivo, implying the WGAR leads to WGAS shift had an underlying genetic basis. Thus, it appeared that the WGAR tumor cells could not metastasize, because of either an intrinsic cellular defect or a host imposed barrier, but that this block could be circumvented through a genetic change in the WGAR tumor cells which was accompanied by reversion of the WGAR phenotype. Non-tumorigenic (tum-) WGAR variants were also obtained, but in these cases the mutagenesis treatment itself appeared responsible for development of the tum- phenotype. The reduced tumorigenicity had an underlying immunological basis, a finding which could be exploited to immunotherapeutically treat established visceral metastases of poorly immunogenic tumors. Throughout these studies, emphasis was placed on the considerable potential of using tumor cell populations having various stable drug-resistant genetic markers to monitor aspects of tumorigenesis, tumor progression, and metastasis.

Leukemia-cell rejection due to T-region encoded antigens

The role of H-2- and T-region products in determining allogeneic cell rejection was evaluated in H-2 congenic and recombinant mice by transplanting A1ATH and A6ATL leukemia cell lines induced in A.TH and A.TL strains, respectively, by Moloney murine leukemia virus.--In K- or D-region incompatible hosts transplant failure was observed, while in I + T-region incompatible hosts either rejection or prolonged survival was seen. In mice preimmunized with spleen cells from I- and/or T-region incompatible donors, leukemia cells were rejected by mice immune only to T-region products, and accepted by mice immune only to I-region products.--Cell-mediated cytotoxicity studies confirmed in vivo results. Secondary CTLs specifically directed against I-region products did not lyse the A1ATH and A6ATL cells, and secondary CTLs from A.TH and A.TL mice sensitized against A6ATL and A1ATH cells respectively exerted a lytic action specific for T-region products, while no activity was observed against I determinants.--The data suggest that tumor-transplant rejection may also be governed by histocompatibility antigens encoded in the T region.

Histocompatibility antigens controlled by the I region of the murine H-2 complex. I. Mapping of H-2A and H-2C loci

Skin grafts were reciprocally exchanged in pairs of congenic lines identical in all genes except those located in the central portion of the H-2 complex. Seven such lines were tested: 6R, B10.AQR, A.TL, A.TH, 7R, 9R, and B10.HTT. In all donor-recipient combinations at least some grafts were rejected. In combinations differing at the IA subregion (and other central H-2 regions or subregions), all first-set grafts were rejected within 3 wk after transplantation, and all second-set grafts were rejected within 10 days. In combinations differing at the IC subregion (and other central regions, but not at the IA subregion) between 60 and 100% of first-set grafts were rejected, but some grafts survived for over 100 days. Most of the second-set grafts were rejected within 1 mo after grafting. This behavior of skin grafts indicated the presence of two histocompatibility loci in the I region, a strong one and a weak one. This conclusion was confirmed by genetic mapping which placed the strong locus in the IA subregion and the weak locus in the IC subregion. We designate the former locus H-2A and the latter H-2C. The same strain combinations used for the skin grafting were also used for determination of the capacity of I-region antigens to function as targets in the in vitro cell-mediated lymphocytotoxicity (CML) assay. Spleen cells from mice presensitized in vivo by skin grafting were restimulated in vitro and tested against 51Cr-labeled concanavalin A or lipopolysaccharide blasts. The testing revealed the presence in the I region of two loci coding for CML-target antigens. The two loci comapped with the H-2A and H-2C loci and were most likely identical to them. As in the skin grafting test, in the CML test, the H-2A antigens evoked stronger response than the H-2C antigens. Rejection of skin grafts across the H-2A and H-2C loci was accompanied by the production of Ia antibodies. Direct cytotoxic and absorption tests with Ia antibodies directed against antigens coded for by the IC subregion revealed the presence of IaC antigens on epidermal cells. We suggest that the products of Ia loci might function as transplantation antigens.

Mutant lines of guinea pig L2C leukemia. I. Deletion of Ia alloantigens is associated with a loss in immunogenicity of tumor-associated transplantation antigens

Five different lines of a strain 2 guinea pig leukemia (L2C) which had been carried in different laboratories share certain chromosomal markers and have a common surface immunoglobulin idiotypic determinant indicating that they have a common origin. All these leukemic lines have on their surface of the B alloantigen (equivalent of the murine H-2K and H-2D antigens) and four of these five lines have on their surface the Ia alloantigens normally present on the strain 2 lymphocytes. The result of a study of the growth and rejection patterns of these leukemias in inbred and random-bred guinea pigs of selected histocompatibility type indicates that both the B and Ia antigens can act as transplantation antigens in guinea pigs. Immunization protection tests in syngeneic animals demonstrated that the four Ia-positive leukemias possessed a tumor-associated transplantation antigen (TATA), while the one Ia-positive leukemias possessed a tumor-associated transplantation antigen (TATA), while the one Ia-negative leukemia by this criteria did not appear to have TATA. However, crisscross immunization protection tests demonstrated that preimmunization of syngeneic animals with an Ia-positive L2C line lead to a subsequent protection against challenge with the Ia-negative leukemia. Immunization with the Ia-negative line never protected against a subsequent challenge with any of the leukemic cells of L2C lines. These results strongly suggest that the Ia-negative leukemia possessed a TATA that can be recognized but is not itself immunogenic, and also indicate that Ia antigens on L2C cells are functionally associated with TATA and can act as immunological carries for tumor transplantation determinants.