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 U DPgalactose : ~~-acety~-D-ga~actosamine-~-D-ga~actosy~transferase and UDPgalactose : 2'-ncetyl-~-glucosamine-~-4-~-galactosyltransferase activities using p-Nitrophenyl-2-acetamido-2-deoxy-a-D-galactopyranoside and p-N~trophenyl-2-acetamido-2-deoxy-~-~-glucopyranos~de 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.1. The p-3-D and 8-4-D-galactosyltransferases activities are found in serum and red cell membranes from all normal individuals.2. Polybrene-positive cells (normal sialic acid content) from Tn bloods have either normal or higher 8-3-D and ~-4-~-galactosyltransferase activities.3. Polybrene-negative cells (low sialic acid content) from Tn bloods have a selective deficiency in P-3-~-galactosyltransferase (T-transferase) activity, but normal or even increased P-4-~-galactosyltransferase activity.4. The serum from all Tn individuals behaves like normal sera in respect of the two galactosyltransferase 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.Polyagglutinable erythrocytes are agglutinated by many sera, irrespective of blood group [l]. The phenomenon arises either by acquisition of extrinsic antigen or by uncovering of receptors, normallyAbbreviations. UDP-Gal, uridine diphospho-D-galactose; Npha-GalNAc, p-nitrophenyl-2-acetam~do-2-deoxy-a-~-galactopyranoside; Nph-P-GlcNAc: p-nitrophenyl-2-acetamido-2-deoxy-~-~-glucopyranoside; NaCl/Pi, phosphate-buffered saline (9 vol. 0.9 % NaCl + 1 vol. isotonic phosphate buffer pH 7

Blood group A cross-reacting epitope defined by monoclonal antibodies NCC-LU-35 and -81 expressed in cancer of blood group O or B individuals: its identification as Tn antigen.

“…The exposure of Tn antigen in various blood cell components has also been observed under a certain acquired human nonmalignant condition resulting from a somatic mutation occurring at the level of bone marrow stem cells and termed "Tn syndrome" (26,29). Tn-positive cells are deficient in (31-3 galactosyltransferase to aGalNAc linked to protein (30).…”

Surface modifications in the platelets of a patient with alpha-N-acetyl-D-galactosamine residues, the Tn-syndrome.

“…These included the high and low molecular weight protein standards used for molecular weight determination by SDS-PAGE. Carrier-free Nal25I (100 mCi/ml in NaOH solution, pH [8][9][10][11] Subjects. The patient with Tn-syndrome (Ba.)…”

“…Exposure of GalNAc residues can be detected by binding studies with Helix pomatia agglutinin (HPA), which is specific for both the a-and ,B-anomer of this sugar (9). Marked alterations in the periodate-Schiff stained patterns were observed following the analysis of membrane glycoproteins (GP) of Tn-erythrocytes by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), with the major sialoglycoprotein (glycophorin A) being particularly decreased in staining intensity (8,10). Glycophorin B was also affected (11).…”

“…A selective loss in f3-3-D-galactosyltransferase (T-transferase) activity in Tn-erythrocytes suggested that the alkali- ' Abbreviations used in this paper: CBR, Coomassie Brilliant Blue R250; CIE, crossed immunoelectrophoresis; GalNAc, N-acetyl-D-galactosamine; GP, glycoprotein; HPA, Helix pomatia agglutinin; HPA-FITC, HPA-fluorescein isothiocyanate; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; TX-100, Triton X-100. labile oligosaccharide chains of the glycophorins were being incompletely synthesized (10,11).…”

Expression of the Tn antigen on erythroid cells from a patient with Tn syndrome

“…This disorder may be associated with a mild hemolytic anemia, leukopenia, or thrombocytopenia, but has also been described in some acute leukemias or myeloproliferative diseases (Bird et al, 1976;Baldwin et al, 1979;Ness et aI., 1979;Vainchenker et al, 1985). The biochemical basis of Tn activation is now well characterized and corresponds to the exposure of an N-acetylgalactosamine residue carried by cell surface glycoproteins, which arises from a selective loss of a 3-/~-D-galactosyltransferase activity in Tn-positive cells (Dahr et al, 1974;Cartron et al, 1978aCartron et al, , 1978bCartron et al, , 1979.…”