Related Experiment Video
Updated: Jul 13, 2026
Murine Heterotopic Heart Transplant Technique
Published on: July 8, 2014
Acute rejection of allografted CTL-susceptible leukemia cells from perforin/Fas ligand double-deficient mice
Hayahito Nomi1, Junko Tashiro-Yamaji, Yumiko Yamamoto
1Department of Physiology, Osaka Medical College, Takatsuki, Japan.
Abstract:
The generation of knockout mice demonstrated that CD4(+), but not CD8(+), T cells were essential for the rejection of allografted skin or heart, presumably because these targets were CTL resistant. In the case of CTL-susceptible targets (e.g., P815 mastocytoma cells and EL-4 or RLmale1 T lymphoma cells), however, it is assumed that the CTL is the effector cell responsible for allograft rejection and that perforin and Fas ligand (FasL) pathways are the killing mechanisms. In the present study, we examined the role of these cytotoxic molecules in the rejection of i.p. allografted CTL-susceptible leukemia cells. Unexpectedly, the allografted leukemia cells were acutely rejected from gld (a mutation of FasL), perforin(-/-), or double-deficient mice. The peritoneal exudate cells from gld or normal mice showed T cell-, TCRalphabeta-, and perforin-dependent cytotoxic activity against the allograft, whereas the exudate cells from perforin(-/-) mice exhibited almost full cytotoxic activity in the presence of Fas-Fc. Furthermore, the infiltrates from double-deficient mice showed a high cytotoxic activity against the allografted cells even in the presence of anti-TCRalphabeta Ab or in the absence of T cells. The cytotoxic cells appeared to be macrophages, because they were Mac-1(+) mononuclear cells with a kidney- or horseshoe-shaped nucleus and because the cytotoxic activity was completely suppressed by the addition of N(G)-monomethyl-l-arginine, an inhibitor of inducible NO synthase. These results indicate that macrophages are ready and available to kill CTL-susceptible allografts when CTLs lack both perforin and FasL molecules.
Insights
Macrophages, not just cytotoxic T cells, reject allografts. Even without perforin or Fas ligand, macrophages eliminate susceptible leukemia cells, highlighting their crucial role in immune response.
Area of Science:
- Immunology
- Transplantation Biology
- Cellular Cytotoxicity
Background:
- Cytotoxic T lymphocytes (CTLs) are traditionally considered key in allograft rejection, utilizing perforin and Fas ligand (FasL) pathways.
- CD4(+) T cells are essential for rejecting CTL-resistant allografts (skin, heart), while CTLs are presumed for CTL-susceptible targets.
Purpose of the Study:
- To investigate the role of cytotoxic molecules (perforin, FasL) in the rejection of intraperitoneally allografted CTL-susceptible leukemia cells.
- To identify the primary effector cells responsible for allograft rejection in the absence of functional CTL cytotoxic mechanisms.
Main Methods:
- Utilized knockout mice deficient in perforin, FasL (gld mutation), or both, to assess allograft rejection.
- Analyzed peritoneal exudate cells and infiltrates for cytotoxic activity using T cell receptor (TCR) and Fas-Fc blockade.
- Characterized cytotoxic cells based on morphology, surface markers (Mac-1), and response to inducible nitric oxide synthase (iNOS) inhibition.
Main Results:
- Allografted leukemia cells were unexpectedly acutely rejected in gld, perforin(-/-), and double-deficient mice.
- Peritoneal exudate cells from perforin(-/-) mice showed significant cytotoxic activity via the Fas-Fc pathway.
- Infiltrates from double-deficient mice exhibited high cytotoxic activity, mediated by Mac-1(+) macrophages expressing iNOS, independent of T cells.
Conclusions:
- Macrophages are potent effector cells capable of rejecting CTL-susceptible allografts, particularly when CTLs lack perforin and FasL.
- This study reveals a previously underappreciated role for macrophages in allograft rejection, expanding our understanding of immune surveillance.
