Stable expression of a selectable myeloproliferative sarcoma virus in murine T lymphocyte and monocyte cell lines

Injection of v-mos-transformed and irradiated macrophages leads to longlasting specific acceptance of MHC-allogeneic heart grafts and specific prolongation of skin graft survival in mice

In vitro studies have revealed that the v-mos-transformed clone mos2 (mos2) of the murine macrophage cell line P388D1 (D1) (H-2d) is capable of inducing a state of specific unresponsiveness in MHC-allogeneic unprimed T cells. Here, we present data on the in vivo relevance of these findings. Male C57bl/6 mice (H-2b) were injected i.p. 6 times with 10(7) of the following irradiated cell types: D1, mos3, mos2, DBA/2-(H-2d) or C3H-(H-2k) spleen macrophages. DBA/2 and C3H skin or heart grafts were performed 10 days after the last injection. The normal rejection time for allogeneic skin was 7.5 days and for allogeneic hearts, was 12.8 days. After injection of D1 or mos3, DBA/2 skin grafts were rejected after 4.5 and 6.5 days, respectively, and the hearts, after 15.4 and 18.6 days, respectively. Third-partly C3H grafts were rejected normally (7.0 days). In contrast, injection of mos2 led to prolongation of DBA skin graft survival to 12.3 days. DBA/2 hearts were accepted for more than 160 days as revealed by heart beating. Again, C3H grafts were rejected normally (11.0 days). DBA/2 skin grafts on day 102 after heart grafting survived for 30 days, indicating hyporesponsiveness against these grafts. These results confirmed the in vitro findings. The mos2 cells obviously induced a state of specific unresponsiveness in otherwise unmanipulated recipients. However, the duration of this unresponsiveness induced by the injection of irradiated cells was dependent on the organ type.

Oncogene transformation can induce tolerogenicity in murine macrophages after down-regulation of immunogenicity without altering major histocompatibility complex antigen expression

In vitro studies on cell lines may allow analyses of the mechanisms of immunogenicity and tolerogenicity in cells. We used a model of oncogenic transformation of an established murine macrophage cell line and report here that one v-mos-transformed clone expressing unaltered high amounts of MHC class I and II antigens does not induce proliferation of unprimed T cells in primary mixed lymphocyte reactions, in sharp contrast to its non-transformed parental cells. Interestingly, this clone induces specific unresponsiveness, as revealed by the lack of responsiveness of MHC-specific T cells when subsequently exposed to the pertinent MHC alloantigens in immunogenic form but unaltered MHC-third party responsiveness of the naive spleen T cells. Furthermore, the accessory function of this clone is strongly reduced. These functional defects could be overcome by the addition of exogenous interleukin-1 alpha (IL-1 alpha). Analysis of mRNA expression showed a significant and selective reduction of IL-1 alpha mRNA levels when compared with parental cells.