Abstract
The non-depleting anti-CD4 mAb RIB5/2 is a powerful inducer of tolerance to MHC-incompatible renal and heart allografts in rat recipients. In vitro the mAb blocks the proliferation and cytokine production of alloreactive T cells. To learn more about the mechanism of anti-CD4-mediated suppression, we applied differential display reverse transcription-PCR to identify differences at mRNA level between T cells stimulated by alloantigen in the presence or absence of anti-CD4 mAb. A sequence alignment of a 550-bp DNA fragment appearing only in anti-CD4 mAb-treated cells resulted in at least 95% homology to a mouse cDNA encoding for the anti-apoptotic protein Bag-1. Further investigation of Bag-1 expression during mixed lymphocyte reactions revealed a three- to fourfold up-regulation of Bag-1 mRNA expression in anti-CD4 mAb-treated allogeneic cultures which was confirmed at protein level. Bag-1 up-regulation was associated with an increase resistance to apoptosis of T cells from anti-CD4 mAb-treated cultures. Application of antisense oligonucleotides specific for Bag-1 reduced Bag-1 protein expression and restored susceptibility to apoptosis. In addition, up-regulation of Bag-1 mRNA could also be detected in graft-infiltrating T cells from anti-CD4 mAb-treated rats in vivo. Thus, the expression of Bag-1 in a subset of anti-CD4 mAb-treated alloreactive T cells conferred resistance against apoptosis, potentially contributing to the long-term survival of these cells.
Publication types
-
Comparative Study
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Adoptive Transfer
-
Animals
-
Antibodies, Monoclonal / pharmacology
-
Apoptosis / drug effects*
-
Apoptosis / genetics
-
CD4 Antigens / immunology
-
CD4 Antigens / physiology*
-
Carrier Proteins / biosynthesis
-
Carrier Proteins / genetics
-
Carrier Proteins / physiology*
-
DNA-Binding Proteins
-
Fas Ligand Protein
-
Gene Expression Regulation / drug effects*
-
Graft Rejection / immunology*
-
Heart Transplantation / immunology
-
Immune Tolerance / immunology
-
Isoantigens / immunology
-
Kidney Transplantation / immunology
-
Lymphocyte Activation
-
Lymphocyte Culture Test, Mixed
-
Membrane Glycoproteins / biosynthesis
-
Membrane Glycoproteins / genetics
-
Mice
-
Polymerase Chain Reaction
-
Proto-Oncogene Proteins / biosynthesis
-
Proto-Oncogene Proteins / genetics
-
Proto-Oncogene Proteins c-bcl-2 / biosynthesis
-
Proto-Oncogene Proteins c-bcl-2 / genetics
-
RNA, Messenger / biosynthesis
-
Radiation Chimera
-
Rats
-
Rats, Inbred Strains
-
Sequence Alignment
-
Spleen / cytology
-
Spleen / immunology
-
T-Lymphocyte Subsets / immunology*
-
T-Lymphocyte Subsets / metabolism
-
Transcription Factors
-
Transplantation, Homologous
-
bcl-2-Associated X Protein
-
bcl-X Protein
Substances
-
Antibodies, Monoclonal
-
BCL2-associated athanogene 1 protein
-
Bcl2l1 protein, mouse
-
Bcl2l1 protein, rat
-
CD4 Antigens
-
Carrier Proteins
-
DNA-Binding Proteins
-
Fas Ligand Protein
-
Fasl protein, mouse
-
Faslg protein, rat
-
Isoantigens
-
Membrane Glycoproteins
-
Proto-Oncogene Proteins
-
Proto-Oncogene Proteins c-bcl-2
-
RNA, Messenger
-
Transcription Factors
-
bcl-2-Associated X Protein
-
bcl-X Protein