Human Leukocyte Antigen Typing in Organ Transplantation: Methods, Clinical Relevance, and Practical Applications

Abstract

ABSTRACT Transplantation of tissues and organs is one of the greatest achievements of this century. Antigens which vary between members of same species are known as allo-antigens. Difference in the allo-antigens between the donor and the recipient represents the antigenic stimulus, which can cause rejections. Adaptive immunity identifies self from non-self. The main objective of the immune response is to identify the cell surface molecules (major histocompatibility complex /MHC) expressed on the donor cells. It is imperative that human leukocyte antigens (HLA) antigens are identified to gauge the mismatches. Presence of pre formed HLA antibodies or formation of de-novo HLA antibodies against these mismatched antigens can lead to antibody mediated rejections and decreased allograft survival. Identification and monitoring of these antibodies pre transplant and post-transplant by performing a virtual cross-match with mismatched donor antigens help in planning and adjusting immunosuppression. A precise and adequate HLA typing of the donor and recipient is required for virtual cross-match. HLA typing technologies have advanced from serological typing to molecular technologies, which can now help identify the donor tissue to allelic level. Methods of HLA typing and their applications with cases have been described in this article.