The use of monoclonal antibodies UCH/β and UCHγ for the antenatal diagnosis of /β‐thalassaemia

S ummary . Monoclonal antibodies for the β‐globin chain of human HbA (UCHβ) and the γ‐globin chain of human HbF (UCHβ) have been made. UCHβ indirectly labelled with rhodamine‐labelled goat anti‐mouse lg and directly fluores‐ceinated UCHy have been used, via double labelling immuno‐fluorescence microscopy, to assay for the presence ofβ‐chains in fetal erythrocytes obtained at fetoscopy from fetuses at risk for β‐thalassaemia major. The results from 111 cases demonstrate that β‐chain synthesis of as low as 1.8% can be detected in fetal erythrocytes. The immunochemical labelling can be rendered more sensitive by the use of biotinylated UCHβ and avidin‐FITC conjugates. This method is rapid and can be used for a sample that is highly contaminated with maternal erythrocytes.