Anti-HLA specificity determined by serum absorption with antigen-masked lymphocytes

Lymphocyte or platelet absorption of multispecific sera is frequently used to establish HLA antibody specificity. Absorption of such sera with cells containing the desired antigenic combinations is often limited by the availability and the HLA characteristics of fresh or frozen cell panels. The method described permits improved absorption of specific HLA antibody with a preparation of cells containing a predetermined single HLA antigen. The procedure involves the screening of the patient's active sera against a panel of frozen cells. Analysis of the positive and negative reactions allows tentative assessment of recipient serum specificities. Cells with a single available HLA antigen type are prepared for serum absorption by suspending the cells in selected antisera to block (mask) HLA surface antigens while leaving just one type of antigen free for monospecific absorption. Following absorption of the test serum with the masked cells, the absorbed serum is then retested against the original panel of frozen cells. Should the results of this screen show a loss of a single HLA activity, the suspected specificity is assigned to the recipient's serum. The use of HLA antigen-masked lymphocytes has proven useful in the definition of HLA antibody specificity.