Appendix L. 
Stem Cells and Tissue Regeneration: 
Lessons from Recipients of Solid Organ Transplantation 
SILVIU ITESCU M.D. 
Director of Transplantation Immunology, Departments of 
Medicine and Surgery, Columbia University, New York, NY 
CONTENTS 
1. OVERVIEW 
2. IMMUNOBIOLOGY OF ORGANTRANSPLANTATION 
The Human Leukocyte Antigens (HLA) 
T Cell Recognition Of Antigen Presented By HLA 
Molecules 
Thymic Education Of T Cells 
T Cell Recognition Of AUo antigens 
Tolerance Induction 
3. IMMUNOSUPPRESSIVE AGENTS COMMONLY USED IN 
ORGAN TRANSPLANT RECIPIENTS: BENEFITS AND 
ADVERSE OUTCOMES 
4. STEM CELL TRANSPLANTATION AND 
IMMUNOSUPPRESSION 
Matemo-Fetal Tolerance 
Immunogenic Characteristics Of Embryonic And 
Adult Stem Cells 
Tolerogenic Effects Of Stem Cell Transplantation 
1. OVERVIEW 
The Major Histocompatibility Complex (MHC) is located on the short 
arm of chromosome 6 in humans and encodes the alloantigens 
known as Human Leukocyte Antigens (HLA), polymorphic cell 
surface molecules which enable the immune system to recognize 
both self and foreign antigens. The class II HLA molecules (HLA-DR, 
HLA-DP, and HLA-DQ) are usually found only on antigen-presenting 
cells such as B lymphocytes, macrophages, and dendritic cells of 
lymphoid organs, and initiate the immune response to foreign 
proteins, including viruses, bacteria, and foreign HLA antigens on 
transplanted organs. 
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