The genetics of teratocarcinoma transplantation: tumor formation in allogeneic hosts by the embryonal carcinoma cell lines F9 and PCC3

T cell receptor delta gene mutant mice: independent generation of alpha beta T cells and programmed rearrangements of gamma delta TCR genes

T cells bearing T cell receptor (TCR) gamma and delta chain heterodimers are first generated early in ontogeny. They form distinct subsets that differ in their TCR repertoires and tissue distribution. Disruption of the mouse TCR C delta gene segment by a gene targeting method caused the complete loss of T cells bearing TCR gamma delta chains, but had little or no effect on the development of T cells bearing TCR alpha beta chains. The analyses of TCR gamma and delta genes in the mutant mice suggest that intracellular mechanisms acting at the level of DNA rearrangement play key roles in the differential gamma and delta gene rearrangements and in the generation of the highly restricted junctional sequences during fetal thymic development.

Resistance to 402AX teratocarcinoma involves immunity to minor histocompatibility antigens

The 402AX teratocarcinoma is a 129/J-derived mouse major histocompatibility complex (MHC) antigen negative tumor that is induced to express H-2b class I antigens during rejection. Resistance to 402AX by MHC allogeneic and syngeneic mice is immunologically mediated and involves the recognition of tumor-associated antigens (TAA) in the context of induced MHC class I antigens. The current studies were undertaken to define the 402AX TAAs. Reconstitution of irradiated susceptible hosts (129/J) with 402AX-primed resistant spleen cells (C57BL/6) results in acute graft-versus-host disease, suggesting that tumor-primed C57BL/6 splenocytes are reactive to tumor genotype (129/J) minor histocompatibility (Hm) antigens. C57BL/6 anti-129/J effector cells, although not directly cytotoxic for 402AX cells, are specifically cold target inhibited by 402AX cells. Genetically susceptible hosts (C3H.SW) immunized to 129/J Hm antigens by skin grafting become resistant to an i.p. challenge of 402AX cells. These results suggest that 129/J Hm antigens may be the TAAs recognized during genetically controlled rejection of the 402AX teratocarcinoma.

402AX teratocarcinoma MHC class I antigen expression is regulated in vivo by Lyt 1, Lyt 2, and L3T4 expressing splenic T cells

The murine 402AX teratocarcinoma is a MHC class I antigen negative tumor of 129 strain origin. Host resistance to the 402AX tumor is genetically controlled. When passed intraperitoneally in genetically resistant mice, the tumor cells are induced to express MHC Class I antigens of the 129 genotype. When passed in genetically susceptible mice, the tumor cells remain MHC class I antigen negative. Earlier studies have demonstrated that resistance to the tumor and regulation of tumor cell MHC class I antigen expression are under the control of the host's immune system. The present studies indicate that splenic Lyt 1-, Lyt 2-, and L3T4-expressing cells regulate tumor cell MHC class I antigen expression, and that these cells require a genetically resistant host environment in which to differentiate. Splenic T cells primed to the 402AX tumor and transferred into genetically susceptible 129 mice give rise to GVHD, suggesting that immunity to the tumor involves reactivity to 129 minor histocompatibility antigens.

H-2 class I antigen expression on mouse teratocarcinoma cell lines

Immunity against PCC3 teratocarcinoma cells (129, H-2b) was induced in allogeneic (C3H, H-2k) mice by preimmunization with L cells (C3H, H-2k) expressing cosmid-introduced Kb or Db genes, but not with nontransfected L cells. In addition, the growth of PCC3 cells in sublethally irradiated (C3H X B6-H-2bm1)F1 and (C3H X B6-H-2bm13)F1 mice bearing the Kbm1 and Dbm13 mutations, respectively, was either prevented, stopped, or delayed in comparison with the (C3H X B6)F1 (k X b) mice, which failed to reject the PCC3 cells. The teratocarcinoma line OC15S was exceptional because it reacted specifically with Kb- and Db-specific (but not Ib-specific) alloantisera, and because Kb- and Db-specific antibodies could be absorbed by OC15S cells. The subpopulation of OC15S cells bearing the ECMA-7 antigen characteristic for embryonic carcinoma (EC) cells was isolated by the fluorescence-activated cell sorter and was shown to react specifically with Kb- and Db-specific antisera. These experiments show that teratocarcinoma cells express antigens similar or identical to the K- and D-region products of differentiated cells. The lack of expression of class I antigens is thus neither a condition nor a consequence of the pluripotentiality of the EC cells. The exact nature of the major histocompatibility complex antigens on EC cells has yet to be established using the methods of molecular biology and biochemistry.

Mice coisogenically immunized against H-2 class I antigens on transfected L cells reject transplanted embryonal carcinoma cells

Evidence is presented of the ability of H-2 class I antigens to function as teratocarcinoma transplantation (Gt) antigens. Coisogenic immunization against H-2 class I antigens expressed on transfected L cells is shown to induce resistance to embryonic carcinoma (EC) cell allografts. The Kb, Db, Dd, and, in appropriate recipients, Ld antigens can function as Gt antigens. The protocol presented may be useful for the molecular identification of other genes encoding histocompatibility antigens.

Minor histocompatibility antigens are developmentally regulated on murine embryonal carcinoma cells and their early differentiated derivatives

Differences in the expression of minor histocompatibility (Hm) alloantigens on two mouse embryonal carcinoma (EC) cell lines and the PYS-2 and T.D.M.-1 differentiated derivatives have been demonstrated by their ability to elicit a cytolytic T lymphocyte response. Experiments involving the use of various responder-target strain combinations and recombinant inbred mice strains have shown that: (1) there are major differences in Hm expression on EC cells compared with differentiated derivatives whose Hm expression appears more like that of adult splenocytes; (2) although both EC cell lines show reduced Hm immunogenicity compared with adult splenocytes, major differences in the expression and possible presentation of Hm between the F9 and PCC3 EC cell lines can be detected by in vivo priming and by in vitro cold competition target experiments. These observations are discussed in relation to the differences in allograft rejection patterns observed with PCC3 and F9 and to possible differences in developmental staging of these cell lines.

Rat natural killer cell and cytotoxic T cell lysis of H-2-negative murine embryonal carcinoma cells

H-2-lacking murine embryonal carcinoma (EC) cells have been proposed as universal targets for natural killer (NK) effectors from different species because their killing appeared to be uncomplicated by potential T cell effector mechanisms (Stern, P. L. et al., Int. J. Cancer 1981. 27:679). While some previous studies had shown that murine cytotoxic T cells were unable to lyse EC cells, rat T killers are shown here to be active against these targets and to be distinguishable from NK cells. Percoll density fractionation of rat peripheral blood lymphocytes enriches in parallel for NK-mediated lysis of both EC or YAC target cells. These NK cells unlike T cells, do not mediate lectin-dependent and cell-mediated cytotoxicity (LDCC) of NK-insensitive target cells. This procedure is thought to reveal the total cytolytic potential of stimulated T cell populations, regardless of specificity. In contrast to previous results with mice, we found that allogeneically primed rat cytotoxic T cells can kill murine EC cells in LDCC and, further, that rat cytotoxic T cells, generated by stimulation with mouse spleen cells in vitro, can lyse murine EC cells directly. This demonstration of T cell lysis of EC cells suggests that either there is a novel mechanism of lysis operating without requirement for major histocompatibility complex (MHC) structures, or EC cells express some hitherto unidentified MHC-like structures on their cell surface.

A gene controlling teratocarcinoma graft rejection mapped inside the t0 haplotype

The embryo-derived teratocarcinoma TC1Ph of the genotype (129 t0/T X C3H)t0/+ and embryonal carcinoma (EC) cell line EC1Ph, established from the TC1Ph, were used as grafts for mice differing only at the T-H-2 interval of chromosome 17. Using exceptional recombinants in this chromosome region a two-gene model of genetic control of EC histocompatibility was proposed. The Cech-1 gene situated at the T end of the T-H-2 interval would control expression of the EC histocompatibility gene located near the H-2 complex.

Growth conditions of F9 embryonal carcinoma cells affect the degree of DNA methylation

We have investigated differences in C pG methylation between F9 embryonal carcinoma cells in vitro and as tumor cells grown in vivo using Msp I and Hpa II restriction isoschizomers. Southerns were hybridized with two low copy number probes, mouse major beta-globin (f7) and a class I, histocompatibility-2 cDNA clone (pH-2d-4). In each case, the tumor-DNA was hypomethylated while the DNA from F9 cells grown in vitro was moderately methylated. We conclude that growth conditions or cell-cell interactions can greatly affect methylation of C pG sites.

A comparative study of the cell cycles of nullipotent and multipotent embryonal carcinoma cell lines during exponential growth

Three embryonal carcinoma (EC) cell lines F9, PCC4 Azal, and PCC3 N/1 with a common origin from the transplantable ascites teratoma OTT6050 were analyzed with regard to cell cycle characteristics during exponential growth in the undifferentiated state. The three lines, in the sequence mentioned, have been shown to represent successive stages in early normal mouse embryogenesis from morula to blastocyst, as reflected in their cell surface antigens. In the multipotent lines an increased intraclonal variability in intermitotic times was found when analyzing family trees. In the PCC3 N/1 line the distribution was almost bimodal. The increased intermitotic time variability was found to be represented in the G1 period that varied from less than 1 hr up to about 6 hr in the PCC3 N/1 line, with a mean value of 3.4 hr. The G1 period of the F9 line had a range of only 3.5 hr, with a mean value of 1.5 hr. The S-G2 period was found to be very similar in length in all three lines.

Male-specific transplantation antigen expression by XY teratocarcinomas PCC7 and 7'

Male-specific antigen expression by XY teratocarcinomas PCC7 and 7' is demonstrated first by the rejection of tumors by female but not by male mice following challenge with these cell lines. Male-specific antigen expression is confirmed by an indirect method in which females are immunized against H-Y antigen by male skin grafts. A variant of PCC7 lacking male-specific antigen expression is described. Analysis of the karyotype and of the DNA from this variant indicate that the loss of male-specific antigen expression is a result of the loss of the Y chromosome. The ability to recover variants that have lost expression of male-specific antigen opens the possibility of their selection after mutagenesis.

Activation of a Qa/Tla class I major histocompatibility antigen gene is a general feature of oncogenesis in the mouse

A cDNA clone corresponding to a mRNA present at elevated levels in transformed fibroblasts encodes a Qa/Tla class I major histocompatibility complex (MHC) antigen. High levels of this mRNA are found in all tumour cells tested; the transcript can undergo alternative splicing; and a repetitive sequence within the transcription unit has the characteristics of a transposable element. The immunological implications of MHC gene activation in tumour cells are discussed.

Teratocarcinoma transplantation antigens are encoded in the H-2 region

Evidence is presented for the existence of teratocarcinoma transplantation antigens (Gt) encoded within the H-2 complex and present also on adult tissues. It has not been possible to separate these Gt loci from H-2 by recombination, and Gt factors map to each end of the H-2 complex. Previous reports indicating separation of all Gt loci from H-2 are reinterpreted. One class of such apparent recombinants has been shown to result from the outgrowth of tumor variants in mice of resistant genotype.

The significance of natural killer activity in the resistance of allogeneic hosts to the embryonal carcinoma cell line F9

A number of mouse strains of known F9 resistance phenotype have been tested for their in vitro natural killer activity against both F9 and YAC target cells. The pattern of in vitro natural killer activity observed does not correlate with the pattern of in vivo F9 resistance. The relative efficiencies of in vitro lysis of the F9 and YAC targets by endogenous natural killer effectors from the 129/Sv, SJL/J, C57Bl/6J, and BALB/cJ strains do, however, parallel each other, even though overall levels of F9 target lysis are very low. Since cold competition experiments indicate that the embryonal carcinoma cell lines tested, F9, PCC4/Aza, and PCC3/A/1, can compete efficiently with YAC as target, this low lysis of embryonal carcinoma cells may be due to an intrinsic lysis resistance. The finding that the parietal endoderm cell line PYS-2 and the trophoectodermal cell line TDM1 also compete with YAC targets in cold competition experiments is discussed in relation to previous reports suggesting that such differentiated derivatives lack natural killer target structures.

Modulation of the immune response to teratocarcinoma in mice sensitized by sperm antigens

Mouse primitive teratocarcinoma cells share a common surface antigen with morulae, preimplantation embryo cells and murine and human spermatozoa. 129/Sv mice were immunized with either spermatozoa and subsequently inoculated with various doses of teratocarcinoma 6050. A significant inhibition or acceleration of tumor growth was observed when compared with controls immunized with compatible fibroblasts. These effects were sex-dependent, both the incidence and tumor growth being suppressed in sperm-immunized males. The opposite effects were observed in sperm-presensitized females. Immune sera obtained from both male and female 129/Sv mice exhibited a high binding activity to human spermatozoa when tested in a cellular radioimmunoassay. Thus, immunization with sperm antigens provides immunotherapeutic and/or enhancing effects in male and female 129/Sv mice, respectively.

Genetics of teratocarcinoma transplantation. III. Genetic control of resistance to F9 tumor formation in allogeneic hosts

Major F9 allograft resistance of strains C57Bl/6J, CBA/J, C3H/He and AKR/J has been shown to be controlled by a small number of recessive genes. These loci are not linked to H-2. Recombinational analysis suggests that the loci responsible for resistance in these strains are at least partially non-overlapping. These results obtained with the blocked F9 embryonal carcinoma cell line are discussed in relation to those reported for embryonal carcinoma strain PCC3/A/l and OTT6050 embryoid bodies, where recessive resistance is H-2 linked.

Strong teratocarcinoma transplantation loci, Gt-1 and Gt-2, flank H-2

Evidence is presented for the existence of two strong murine teratocarcinoma transplantation antigens (Gt) on the cell line PCC3. It is shown that the loci governing expression of these antigens are linked to the H-2 complex. These loci have been further mapped with respect to the brachyury marker (T) and H-2: Gt-1 lies 5 +/- 2 crossover units proximal to H-2 and 12 +/- 2 crossover units distal to T; Gt-2 lies 21 +/- 4 crossover units distal to H-2. It is possible that these strong transplantation antigens provide an embryonic analogue to the adult major histocompatibility system.

Teratocarcinoma transplantation rejection loci: genetic localization of the Gt-1 locus on chromosome 17 and the expression of alternate alleles

A series of congenic mice on the BALB/c genetic background have been employed to localize a teratocarcinoma transplantation rejection locus, Gt-1, to the K side of the H-2 locus on chromosome 17. Previous studies have placed the Gt-1sv allele about 8 centimorgans away from the H-2b or H-2bv1 locus. Teratocarcinomas derived from 129/sv mice, Gt-1sv (H-2Kbv1/H-2Dbv1), are rejected by BALB/c(H-2Kd/H-2Dd) and BALB.G mice (H-2Kd/H2D-b, but form tumors in BALB.B (H-2Kb/H2Db) and BALB/5R5 mice (H-2Kb/H2Dd). In the reciprocal tumor-rejection test, a BALB/c teratocarcinoma was rejected by immunized BALB.B mice, but formed tumors in the immunized isogenic BALB/c mouse. These studies demonstrate the reciprocal expression of two Gt-1 alleles, one Gt-1c, in BALB/c mice, and the other, Gt-1sv, in the congenic BALB.B mice, Shedlovsky and co-workers have placed the GT-1 locus in a similar location on the K side of the H-2 locus on chromosome 17.

Antibody response to embryonal carcinoma cells in syngeneic mice

The immunoglobulin (Ig) classes and subclasses of the specific antibodies contained in antisera raised in male 129/Sv mice against cells of a syngeneic clonal line of embryonal carcinoma (F9) have been determined. Cytotoxic activity was found associated almost exclusively with anti-F9 IgM (micro kappa) antibodies. A large part of anti-F9 activity was found associated with IgG1 (gamma 1 kappa and presumably also gamma 1 lambda) antibodies, and was detectable only by direct immunofluorescence. Traces of specific IgG2a and IgG2b antibodies were also found. No IgG3 and IgA antibodies reacting with embryonal carcinoma cells were detectable under these conditions. The serum of F9 tumor-bearing animals had a very similar Ig composition. Furthermore, IgM and IgG1, but not IgG2 antibodies, were detected at the surface of in vivo growing F9 tumor cells.