Temporal sequence of transcription of perforin, Fas ligand, and tumor necrosis factor-alpha genes in rejecting skin allografts.
BACKGROUND
Perforin, Fas ligand (FasL), and tumor necrosis factor-alpha (TNF-alpha) have been implicated in cytolytic T lymphocyte (CTL) effector function. However, the relative roles of these effector molecules in allograft rejection are unclear, and there has been no rigorous quantitation of transcription of the respective genes throughout the period from transplantation to rejection.


METHODS
We orthotopically transplanted mouse tail skin allografts and estimated the numbers of transcripts of these genes expressed by graft-infiltrating T cells with rigorous quantitative, competitive reverse transcribed PCR (QC-RT-PCR) that enabled the comparison of transcription of different genes.


RESULTS
Perforin and FasL mRNA levels correlated closely with the rejection of allografts by normal hosts over the 4 days preceding rejection. Antibody-mediated depletion of host CD4+ T cells retarded perforin transcription and significantly suppressed FasL transcription, suggesting FasL was not required for allograft rejection. TNF-alpha transcription was the highest of these genes in this time period, but these levels were dwarfed by TNF-alpha transcription at 24 hr posttransplant when transcription in both autografts and allografts was 30-fold higher than in allografts on the day before rejection. Elimination of the function of these single or paired genes through genetic mutation or antibody treatment had no significant effect on the speed of rejection.


CONCLUSIONS
The levels of perforin and FasL transcription appeared to be related to the process of allograft rejection in normal hosts. However, TNF-alpha transcription was highest during the posttransplant period suggesting that the principal role of TNF-alpha is in wound-healing rather than the effector phase of rejection.
Borson
N D
ND
Department of Immunology, Mayo Foundation, Rochester, Minnesota 55905, USA.
Strausbauch
M A
MA
Kennedy
R B
RB
Oda
R P
RP
Landers
J P
JP
Wettstein
P J
PJ
D000818:Animals; D000954:Antigens, Surface / Q000235:genetics*; D017209:Apoptosis / Q000235:genetics; D018791:CD4 Lymphocyte Count; D053222:Fas Ligand Protein; D006084:Graft Rejection; D007376:Interleukin-2 / Q000235:genetics; D008024:Ligands; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D054353:Perforin; D016133:Polymerase Chain Reaction; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger / Q000378:metabolism; D016038:Skin Transplantation; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014184:Transplantation, Homologous; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*; D014945:Wound Healing / Q000235:genetics; D019014:fas Receptor / Q000235:genetics*
D000954:Antigens, Surface; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D007376:Interleukin-2; D008024:Ligands; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; D054353:Perforin