Demonstration of T‐Transferase Deficiency in Tn‐Polyagglutinable Blood Samples

Abstract

The serum and red cell membranes from seven Tn individuals have been tentatively characterized for the UDPgalactose: N ‐acetyl‐ d ‐galactosamine‐β‐ d ‐galactosyltransferase and UDPgalactose: N ‐acetyl‐ d ‐glucosamine‐β‐4‐ d ‐galactosyltransferase activities using p ‐Nitrophenyl‐2‐acetamido‐2‐deoxy‐α‐ d ‐galactopyranoside and p ‐Nitrophenyl‐2‐acetamido‐2‐deoxy‐β‐ d ‐glucopyranoside respectively as low molecular weight acceptors. In five cases, Tn‐positive and Tn‐negative red cells were at first separated by Polybrene differential aggregation. The following conclusions have been drawn. The β‐3‐ d and β‐4‐ d ‐galactosyltransferases activities are found in serum and red cell membranes from all normal individuals. Polybrene‐positive cells (normal sialic acid content) from Tn bloods have either normal or higher β‐3‐ d and β‐4‐ d ‐galactosyltransferases activities. Polybrene‐negative cells (low sialic acid content) from Tn bloods have a selective deficiency in β‐3‐ d ‐galactosyltransferase (T‐transferase) activity, but normal or even increased β‐4‐ d ‐galactosyl‐transferase activity. The serum from all Tn individuals behaves like normal sera in respect of the two galactosyl‐transferase activities. The serum may also be used as source of enzyme for conversion in vitro of Tn to T‐reactive erythrocytes. The above data strongly support the view that Tn‐polyagglutination results from a somatic mutation in stem cells of haematopoietic tissue which involves a single genetic step in red cell glycoprotein synthesis. It also provides further evidence of a dual population of erythrocytes in each Tn blood sample and suggests that T‐transferase found in serum is produced in unidentified cells of the organism. No difference has been noticed between apparently healthy Tn donors and Tn patients.