Four examples of anti-TSEN and three of TSEN-positive erythrocytes.
BACKGROUND
TSEN (MNS33) is a low-incidence antigen in the MNS blood group system encoded by hybrid glycophorin genes. TSEN is expressed by a unique amino acid sequence that results from the junction of GPA(58) to GPB(27), if the GPB carries S antigen. Until this study, only one example of anti-TSEN had been found. Antibody screening red blood cells (RBCs) positive for both S and s (ref. No. C873) reacted with four patient sera. Initially, the RBCs had been typed as S+s+, but later were typed as S-s+ in another laboratory. Two other RBC samples, one from a volunteer blood donor (D.L.), the other from a patient whose serum contained anti-En(a)FR (J.S.), also gave anomalous results when tested with anti-S. We suspected the presence of TSEN-positive hybrids on all three RBC samples.


METHODS
Reactive sera (O.B., E.C., S.K., R.F.) were tested against RBCs with normal MNS phenotypes and with TSEN-positive RBCs. The RBCs of D.L., J.S. and C873 were tested with anti-S whose reactivity with S+s+ TSEN+ RBCs had been established previously, and with the original example of anti-TSEN. Immunoblotting was performed on the C873, D.L. and J.S. RBC membranes using a monoclonal antibody to an epitope common to both glycophorin A and glycophorin B.


RESULTS
The sera from O.B., E.C., S.K. and R.F. were strongly reactive on the indirect antiglobulin test with TSEN+ RBCs. The RBCs of C873, D.L. and J.S. were typed as TSEN+. Immunoblotting pattern of D.L. and C873 were consistent with TSEN heterozygotes, while that of J.S. was consistent with a TSEN homozygote.


CONCLUSIONS
Based on the estimated number of screening events with C873 RBCs, the incidence of anti-TSEN is approximately 1 in 20,000 sera. The antibody is found in patients with and without documented exposure to allogeneic RBCs. All known examples of anti-TSEN are IgG, but their clinical significance is not known.
Storry
J R
JR
New York Blood Center, New York, NY 10021, USA. jstorry@nybc.org
Lindsay
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G
Rolih
S
S
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Rodberg
K
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Harris
T
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Reid
M E
ME
D000328:Adult; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D001788:Blood Grouping and Crossmatching; D015153:Blotting, Western; D003298:Coombs Test; D000939:Epitopes / Q000276:immunology*; D004910:Erythrocyte Membrane / Q000276:immunology*; D005091:Exons / Q000235:genetics; D005260:Female; D005838:Genotype; D006021:Glycophorins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D007518:Isoantibodies / Q000276:immunology*; D008951:MNSs Blood-Group System; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D011933:Reagent Kits, Diagnostic; D011995:Recombination, Genetic
D000911:Antibodies, Monoclonal; D000939:Epitopes; D006021:Glycophorins; D007074:Immunoglobulin G; D007518:Isoantibodies; D008951:MNSs Blood-Group System; D011933:Reagent Kits, Diagnostic