Anti-HPA-la platelet antibody levels in pregnant women with a history
of fetomaternal alloimmune thrombocytopenia (FMAIT) were monitored lon
gitudinally using the monoclonal antibody immobilisation of platelet a
ntigens (MAIPA) assay, in order to examine any variation in optical de
nsity (OD) readings obtained over the course of pregnancy and after de
livery. Seven women were selected; 4 were studied retrospectively and
3 prospectively (the latter being treated with intravenous gammaglobul
in; IVGG). Levels of anti-HPA-la were measured at various intervals af
ter delivery of the first affected infant, to post delivery of the fol
lowing affected infant. A decrease in MAIPA OD was demonstrated in all
patients during the course of these pregnancies. This assay is a usef
ul tool for monitoring anti-HPA-la in women with a history of infants
affected with FMAIT. A maternal antibody 'resting' level prior to, or
early in the first trimester, must be established for comparison.