Platelet absorption on the test tray (PATT): A rapid method for the screening of HLA class II antibodies using the two‐colour fluorescence method

Abstract

Several strategies have been proposed for the screening of alloantisera towards HLA class II antigens. Most often the absorption of the sera with platelets is required in order to remove their anti‐HLA‐A, B, C activity. We have developed a simple micromethod for platelet absorption of sera: platelet absorption on the test tray (PATT); 0.5 μl of platelet suspension is incubated with 0.5 μ1 of the serum to be absorbed in the same tray which is subsequently used for the microlymphocytotox‐icity by the two‐colour fluorescence method. This technique is proved to be almost as efficient as classical absorption procedures: out of 44 anti‐HLA‐A, B sera the T‐sell activity is completely removed in 43 by a classical procedure as compared to 41 by PATT; only 8% discrepancies were found among 394 reactions. PATT was then used for anti‐B lymphocyte screening in 419 anti‐HLA‐A,B sera: 4% of the sera remained cytotoxic towards T and B lymphocytes while 35% reacted only with B cells, several of them being DR specific. PATT can also be useful for T/B lymphocyte differential cross‐matches before kidney transplantation. The method is now routinely used in our laboratory for anti‐HLA class II antibody screening.

Detection of HLA Antibodies in Organ Transplant Recipients – Triumphs and Challenges of the Solid Phase Bead Assay

“…By testing against both T (which express HLA class I) and B lymphocytes (which express both HLA class I and II) it is possible to characterize both class I and class II antibodies when they occur together. An added step of absorbing sera with platelets, which express HLA class I but not class II, prior to testing enables the determination of class II antibody specificity without the added complicating factor of co-occurring class I antibodies (12). …”

Depletion of donor-specific anti-HLA A2 alloantibodies in a hematopoietic cell transplant recipient using directed mismatched platelet transfusions

“…Here we decided to use directed mismatched platelet transfusions without additional plasmapheresis. Platelets express HLA class I but not class II antigens on their cell surface [ 15 ], and can be used to deplete antibodies against HLA class I antigens in vitro [ 16 ], and also in vivo [ 5 , 17 ]. For desensitization, seven apheresis platelet preparations with an average platelet content of 3.2 × 10 11 platelets per unit were transfused.…”