Typing and detection of antibodies in the PLA system (platelet). Application to the study of neonatal thrombopenia by feto-maternal PLA allo-immunisation.

A platelet indirect radio-active Coombs test has been described. The technique for purification and labelling the antiglobulin has been precised. This test allows the typing of platelets in the PLA system and the study of sera from mothers of thrombocytopenic child. As examples, four families of neonatal thrombocytopenia are reported, with PLA1 negative mother. In the serum of three of these mothers, we could demonstrate anti-PLA antibodies in spite of a negative platelet complement fixation. This test has many advantages compared to other tests such as platelet complement fixation, assay for blocking antibodies or antiglobulin consumption: it gives objective and quantitative results and is highly reproducible, anticomplementary serum may be tested. It has enabled us to select PLA1 negative donors for exsanguino-transfusions of thrombocytopenic children born from PLA1 negative mothers.