Association of prior sensitizing events with anti-human leukocyte antigen antibodies: An analysis of renal transplant recipients in a tertiary care centre in South India.

Traditionally, sensitizing events such as previous pregnancies, previous transfusions and prior transplants result in the production of anti-Human Leukocyte Antigen (HLA) antibodies. However, it has been observed that, anti-HLA antibodies have been detected in many patients with no prior history of sensitizing events. This retrospective study analysed the most recent 100 consecutive Single Antigen Bead (SAB) assay results performed on 100 patients. The SAB assay is used routinely to detect anti-HLA antibodies in transplant recipients. Results of the SAB assay were analyzed and subsequently studied to see if a correlation existed between sensitizing events, the type of events and presence of antibody. Analysis showed that 77% (77/100) had anti-HLA antibodies. 61 out of 100 patients had prior sensitizing events while the remaining 39 had none. Both these groups showed an almost equal percent of patients with anti-HLA antibodies 77% (47/61) and 76.9% (30/39) respectively. A single sensitizing event was seen in 54.1% (33/61) patients including previous transfusions in 29.5% (18/61), pregnancies in 11.4% (7/61) and prior transplant in 13.1% (8/61). Our study suggests that irrespective of whether patients have prior sensitizing events or not, patients run the risks of alloimmunization, and therefore appropriate screening tests should be included in the pre-transplant compatibility algorithm.