Vox Sang. 31: 337-343 (1976)

The Rare Blood Group Antigen, Wu

L. KORNSTAD, P. HOWELL, J. JBRGENSEN, A. M. HEIER LARSEN and L. D. WADS WORTH

National Blood Group Reference Laboratory, State Institute of Public Health, Oslo, National Blood Transfusion Service, North Western Regional Health Authority, Man- Chester, and Blood Bank and Blood Grouping Laboratory, Municipal Hospital, Aarhus

Abstract. The inheritance of the Wu antigen in three families is described. The observa- tions suggest that the antigen is inherited as a Mendelian dominant character. Wu segre- gates independently of sex and of the ABO, MNSs, Rh, Lutheran, DufTy and Kidd blood group systems. Independence of Kell is also quite likely. Wu is a very rare antigen. The corresponding antibody is not as infrequent. Anti-Wu occurs as a ‘naturally occurring’ antibody, often together with antibodies against other rare antigens.

The Wu antigen was discovered in 1966 by HEIST^ 121. In screening patients’ sera for irregular antibodies, an antibody was found which reacted with the cells of one blood donor only, Mrs. Wulfsberg. A further 8,406 sera from patients were tested against the donor cells and revealed three additional examples of anti-Wu. No further example of the antigen was found in testing 652 random donor samples [2]. The father of Mrs. Wu. was shown to have the same antigen as the proposita, but as the family was small, no information could be obtained regarding the inheritance of the antigen or its independence from the established blood group systems. The inheritance of the Wu antigen has been studied in three additional families, the first new propositus being found during a systematic search for the antigen and the other two as the result of an incompatibility in a pre-operative cross-match.

Detection of the Propositi

A search for the Wu antigen was made in Oslo in 1967 and 1,511 people were negative when tested against serum LMT [3]. During the period 1969-74 about 9,500 Oslo blood

Received: October 21, 1975; accepted: December 17. 1975.

338 KORNSTAD et al.

donors were tested with the same serum which was used undiluted at 18°C against cells suspended in saline. As this technique gave only a 2+ reaction with fresh Wu+ cells, the last 7,000 donors were also tested with another anti-Wu serum (Kirk.).

These screening tests revealed only one further Wu + , Mr. T. And., whose ceIls gave a distinct reaction with both antisera. The sera also contained several other antibodies, as will be described later. The identity between the antigen on Mr. And.’s cells and the original Wu + cells was proved by cross-absorption and heat elution studies.

The next example of the antigen was found in Manchester during a pre-operative cross-match of the serum of Mrs. Blo. against the cells of a group A Rh+ donor, Mr. W. San. Incompatibility was found in saline and albumin agglutination tests at 20 and 37°C and complete agglutination was observed in carrying out the antiglobulin test. Extensive tests of Mrs. Blo.’s serum revealed activity against a number of cells carrying different low frequency antigens, among them cells from the known Wu+ members of the And. family. In addition to serum Blo., the cells of Mr. San. were agglutinated by three other sera known to contain anti-Wu as well as some other antibodies. The presence of the Wu antigen on Mr. San.’s cells was eventually proved by absorption and fixationelution tests.

A further 1,323 English donors were tested with serum Blo. without encountering an additional positive. Screening of 235 random A and AB donor sera against the cells of Mr. San. at Manchester revealed a serum Szulc, which seems to contain anti-Wu only.

The fourth family (G. B. J., Aarhus) with the antigen was found during a cross-match of the serum of Mr. E. C. against the cells of Mr. G. B. J. A further 523 unrelated persons were tested without encountering an additional positive. Screening of 172 sera from donors of group A or AB revealed four sera with a very weak anti-Wu.

Serological Independence

Negative reactions were obtained in testing the cells of the Wu + members of the And., San. and/or G. B. J. families against antisera to the following low frequency antigens: CP, Far, He, Hil, MI, Me, Mia, Mta, Mur, MY, Nya, Ria, Sj, Sta, Sul, Tm, Vr, Vw, Cw, Cx, E W , V, VS, Rh32, Rh33, Rh35, Kpa, Jsa, Ula, Wka, Dia, Ytb, Cob, Bua (SC~), Ina, An&, Bi, Bpa, By, Good, Gf, Heibel, Jna, Levay, Lsa, Moa, Pta, Rd, Re&, RP, Swa, Toa, Wb, Wra, Bea, Evans, Goa, Zd, Haakestad, Skjelbred, Allen, Balkin, Bell, Bowyer, Donavieski, Dropik, Duch, Evelyn, Hollister, Kaj, Marcus, Middel, Milano, Oldeide, Orriss, Rios, Sadler, Tra, Raddon. None of the San. samples reacted with lectins capable of detecting polyagglutinability.

Family Studies

The pedigrees of the families And., San. and G. B. J. are given in figures 1-3. The Wu antigen was demonstrated in three generations in the families

The Rare Blood Group Antigen, Wu

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And. and San. Among the offspring from the matings Wu+ x Wu- (counting 1-1 in figure 3 as + and 11-8 as -) there were 14 Wu+ and 14 Wu - persons. The propositi were excluded from the count as children, but not as parents. The propositi had 5 Wu+ and 12 Wu- sibs. Although Mr. San. is the only Wu + in the first generation studied of this family, the observations suggest that the Wu antigen is inherited as a Mendelian dominant character.

Figure 1 demonstrates independent segregation of Wu and the MNSs system in the And. family. A study of the San. family (fig. 2) was more revealing in that Wu seems to be independent of Rh and can be seen to segregate independently of sex and the MNSs, Lutheran and Duffy systems. The G. B. J. family (fig. 3) showed that Wu segregated independently of sex and of the ABO, MNSs, Duffy and Kidd systems. Independence of Kell is also very likely: this would be the case if either 1-1 or 11-8 were kk. Unfortunately, a blood sample from 11-8 was unobtainable. The study was not informative regarding the P and Lewis systems.

340 KORNSTAD et al.

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342 KORNSTAD et al.

against rare antigens : anti-Wra, anti-Bpa, anti-Pta, anti-Tra, anti-Middel, anti-Bowyer, and very weak anti-Skjelbred.

A second antiserum, serum Kirk., was originally found by screening sera from Oslo blood donors against Jn(a +) cells. It was the only one with anti-Jna activity among more than 3,000 sera. It was later found to contain anti-Wu as well. Again, the antibody reacted with saline suspended cells, distinctly better at 18 than at 37°C. The anti-Wu was non-reactive by the indirect antiglobulin technique, but reacted with papain-treated cells. Serum Kirk. also contains the following antibodies against infrequent antigens : anti-Wra, anti-Bp&, anti-Pta, anti-RP, anti-Middel, anti-Haakestad, anti- Oldeide and anti-Bowyer.

The anti-Wu of serum Blo. also seems to be ‘naturally occurring’. Mrs. Blo. is not known to have been transfused and her serum is compatible with the cells of her husband. Serum Blo. is the strongest anti-Wu so far observed. The antibody is essentially a saline agglutinin giving optimum reactions at 20°C to a titre of 64. The antibody also shows good reactivity using Low’s enzyme technique and with papain- or ficin-treated cells. However, enzyme treatment also tends to give some non-specific agglutina- tion. The reactivity of the agglutinin was completely destroyed following treatment with 2-mercaptoethanol, and after fractionation using Sephadex G-200 the antibody activity was detected only in the fraction known to contain IgM. In addition to anti-Wu, serum Blo. contains antibodies against the following rare antigens: Wra, Vw, Ria, Swa, Jna, Pta, Bpa, Orriss, Skjelbred, Oldeide and Bowyer. It aIso contains a weak anti-Moa. The anti- Wu of serum Szulc is also saline reacting but is distinctly less potent than serum Blo.

The anti-Wu of Mr. E. C., who has never been transfused, is also a saline agglutinin detectable at 4, 20 and 37°C using untreated or enzyme treated (papain, trypsin, bromelin) cells. The antibody could not be de- monstrated using albumin or antiglobulin techniques. Although the titre of the antibody was low (1 :4) the undiluted serum gave a strong (+ + +) reaction which was abolished by treatment with 2-mercaptoethanol. It could be absorbed by and eluted from Wu-positive cells from the family And.

Anti-Wu is not as rare as the corresponding antigen, but it is still rela- tively infrequent. As previously observed for antisera against other rare antigens [l], anti-Wu also often occurs together with antibodies against other infrequent antigens. Evidently some people have a special propensity for forming such antibodies.

The Rare Blood Group Antigen, Wu 343

Acknowledgements

The authors are grateful to the families of Mr. T. And., Mrs. Blo., Mr. G. B. J. and Mr. W. San. for their co-operation and to Dr. H. HEISTO, Blood Bank and Immuno- haematology Laboratory, Ullevaal Hospital, Oslo, for samples of the original Wu + cells. They also thank Dr. R. SANGER and M m J. GAVIN, MRC Blood Group Unit, London. for extensive testing of Mrs. L. And. and Mr. G. B. J., and Miss J. POOLE and Dr. C. M. GILD, MRC Blood Group Reference Laboratory, London, for testing Mr. San. for many low frequency antigens and confirming the San. family grouping results.

References

1 CLEGHORN, T. E.: The occurrence of certain rare blood group factors in Britain; thesis

2 HEISTij, H.: Personal commun. (1966, 1967); cit. RACE and SANGER [4]. 3 KORNSTAD, L. and WOLTHUIS, K.: Observations (1967); cit. RACE and SANGER [4]. 4 RACE, R. R. and SANGER, R.: Blood groups in man; 5th ed. (Blackwell, Oxford 1968).

Sheffield (1961).

Dr. LEIF KORNSTAD, Statens Institutt for Folkehelse, Postuttak, Oslo 1 (Norway)