Co‐occurrence of anti‐Ag and anti‐Australia Antibodies in Transfused Patients

The sera from 158 transfused thalassemic patients have been tested for the presence of anti‐Ag and anti‐Australia antibodies. Twenty per cent of the anti‐Ag sera were found to contain anti‐Au antibodies simultaneously. When these sera are employed in Ag typing of sera from populations and families living in areas with high incidence of Au(1) carriers or from patients with high frequency of Australia antigen, several kinds of errors might occur: (a) erroneously high frequency of apparently Ag reactors; (b) possibility of scoring as illegitimate Au(1) children from Ag(‐) × Ag(‐) matings; (c) apparently new specificities in the Ag system. All these possible errors have been considered studying the distribution of the Ag(x), (z), and (y) factors in 120 Down's syndrome patients and in Ag(‐) × Ag(‐) matings the offspring of which included a Down's syndrome child. The use of these antisera in Au(1) screening may lead to the detection of ‘false’ positives. Methods are suggested to avoid such errors.