An Update on Crossmatch Techniques in Transplantation

Abstract

Crossmatch techniques formulated nearly a half century ago remain the bedrock of transplantation science. While initial methods relied on complement dependent cytotoxicity. More recently additions to the transplant physician's immunologic armamentarium have arrived in both cell-based as well as solid phase assays. Flow cytometry is useful in previously sensitized patients while bead technology has revolutionised HLA antibody testing. The virtual crossmatch uses bead technology to detect specific recipient antibodies without requiring donor serum. We present a concise review of the techniques available, their basis and comparison between them so as to better understand their respective applications.

Histocompatibility Testing: A Fundamental Aspect of Renal Transplant Workup

“…The T and B cells are separately examined against the recipient's serum [9]. The humoral immunological response operates through the activation of the complement system via the classical pathway [2]. To illustrate the consequences of this sequence, complement (usually from rabbit serum) is introduced to the recipient's serum mixed with the prospective donor's lymphocytes, resulting in the observation of cell lysis in the lymphocytes [2].…”

“…Advances in testing methods continue to enhance the precision and efficiency of histocompatibility assessments. Significant progress in histocompatibility testing has revolutionized the safety of renal transplantation procedures, leading to a notable reduction in incidents of renal rejection [2]. Medawar, Billingham, and others have highlighted the key role of the immune system in recognizing and rejecting foreign tissues through a process termed sensitization.…”

“…Pretransplant histocompatibility testing relies on critical assessments such as human leukocyte antigen (HLA) typing of both the prospective donor and recipient and crossmatches conducted through complement-dependent cytotoxicity (CDC) or flow-cytometerbased methods commonly known as flow cytometry crossmatch (FCXM) [3][4][5]. The evolution of these histocompatibility testing technologies, evolving since the 1960s, has sharpened predictive methodologies for graft (renal) rejection [2,6]. Progression from polymerase chain reaction (PCR)-based HLA typing to sequence-based methods and from cell-based crossmatches to virtual crossmatches using advanced solid-phase platforms has strengthened our comprehension of donor-specific antibodies (DSAs).…”

Evaluation of rapid optimized flow cytometry crossmatch (Halifaster) in living donor kidney transplantation

“…It is both highly sensitive and specific, also allowing for the detection of low levels of DSAs that might otherwise go unnoticed in a classical complement‐dependent cytotoxicity crossmatch. This helps identify potential immunological barriers to successful transplantation 6,7 . In the context of living donors, the importance of FCXM cannot be overstated, as it aids in selecting the most suitable donor, thereby improving transplant outcomes.…”

“…This helps identify potential immunological barriers to successful transplantation. 6,7 In the context of living donors, the importance of FCXM cannot be overstated, as it aids in selecting the most suitable donor, thereby improving transplant outcomes. Hence, FCXM is a crucial pre-transplantation test, that has revolutionized solid organ transplantation and has become essential in transplant patient risk stratification.…”