HLA-B27 DETERMINATION USING SEROLOGICAL METHODS - A COMPARISON OF ENZYME-IMMUNOASSAY AND A MICROLYMPHOCYTOTOXIC TEST WITH FLOW-CYTOMETRY AND A MOLECULAR BIOLOGICAL ASSAY

Typing for HLA-B27 is routinely performed in patients with seronegativ e spondarthritides. Besides the microlymphocytotoxic test (MLCT), othe r serological techniques have been developed such as enzyme immunoassa ys (EIA) using serum or plasma as a source for the determination of so luble HLA-B27 (sHLA-B27) and flow cytometric (FC) methods. The aim of the present study was to check the accuracy and reliability of the EIA for sHLA-B27 in comparison to the MLCT using antibodies against HLA-B 27 and cross-reacting specificities (CRS), as well as an FC method and a molecular biological method. Any discrepant results should be typed with the MLCT using a complete panel of anti-HLA-class I antibodies, with FC and with a molecular biological technique. The EIA should also be repeated in those patients, using serum and plasma from a new veni puncture. In 81 patients with rheumatic disorders, the EIA and the MLC T using antibodies against HLA-B27 and CRS were performed. Based on th e MLCT with a complete panel of anti-HLA-class I antibodies as a stand ard, discrepant test results were obtained for 9 out of 81 patients wi th the MLCT using antibodies against HLA-B27 and CRS and with the EIA. The following wrong results occurred: in the MLCT with anti-HLA-B27 a nd CRS, there were two false-negative results; in the EIA there were f our false-negative and one false-positive results; one sample was unde terminable. In comparison with the MLCT, including the complete panel of HLA-class I antibodies, as well as with a molecular biological tech nique, typing with FC showed a complete concordance. Our investigation s demonstrated that for routine typing for HLA-B27 the MLCT cannot be replaced by EIA because of a significant number of mistypings. The MLC T performed only with antibodies against HLA-B27 and CRS may also lead to typing errors. No errors were detected using flow cytometry. If on ly serological methods can be performed in a laboratory a combination of flow cytometry and MLCT could therefore enhance the safety of HLA-B 27 typing.