Tumour-associated and differentiation antigens on the carbohydrate moieties of mucin-type glycoproteins

607th MEETING, LONDON Much-Type G lycoproteins zy zyx zy 59 1 Carbohydrate Group Colloquium organized and edited by T. Feizi (Harrow) zyxwvu zyxwvutsr Tumour-associated and differentiation antigens on the carbohydrate moieties of mucin-type glycoproteins TEN FEIZI, H. C. GOOI, R. A. CHILDS, J. K. PICARD, K. UEMURA,* L. M. LOOMES, S. J. THORPE and E. F. HOUNSELL Applied Immunochemistry Research Group, MRC Clinical Research Centre, Warford Road, Harrow, Middx. H A 1 3UJ. U . K . Introduction The term mucin is used to describe the high molecular weight glycoproteins which are major components of mucus, the seroviscous material secreted by various epithelial tissues, and to which are attached numerous carbohydrate chains. As many as 200 closely spaced (clustered) carbohydrate chains per 250 kilodaltons of glycoprotein may be attached by a linkage between the N-acetylgalactosamine and the oxygen atom of serine or threonine residues (reviewed by Hounsell & Feizi, 1982). This linkage is termed 0-glycosidic (or mucin-type) in distinction from a second type of carbohydrate-protein linkage (N-glycosidic) in which N-acetylglucosamine is joined to the nitrogen of asparagine residues (Kornfeld & Kornfeld, 1980). The carbohydrate chains of mucins vary greatly in the number of Present address: Department of Biochemistry, Institute of Adaptation Medicine, Shinshu University, Matsumoto 390, Japan. Abbreviation used: PNL, peanut lectin. monosaccharides they contain. In spite of this apparent complexity, there appears to be a considerable order in their biosynthesis. Thus, three structurally and antigenically distinct domains, core, backbone and peripheral, are recognized. These are shown schematically in Fig. 1. Domains of the carbohydrate chains of mucins Core regions. Five types of core region structure are known. Biosynthesis of this region may not proceed beyond structure (I) Gal NAc-0-SerlThr Alternatively chain elongation may occur giving rise to four additional types of core region structure containing galactose and/or N-acetylglucosamine residues linked to Nacetylgalactosamine residues of structure (I) as follows : (PNL receptor) zyx Galfll-+3GalNAc GlcNAcPl L !G~INA~ 7 Gala1 GlcNAcPl -+ 3GalNAc Monosaccharides: regions Backbone Peripheral I Fig. 1. Schematic presentation of carbohydrate chains of a mucin-type glycoprotein Only a part of the high molecular weight glycoprotein is shown. It is envisaged that numerous closely spaced oligosaccharides of varying length are attached to serine or threonine residues of the polypeptide moiety. Vol. 12 (111) (IV) zyxwvutsrq \;GaINAc 0 Core (11) GlcNAcPl r GlcNAcPl Peptide (1) (V) Structure (11) constitutes the blood group T determinant recognized by PNL (Periera et al., 1976), and this is also expressed on structure (111) and on structure (VI) (see below). Backbone regions. The backbone regions usually consist of alternating galactose and N-acetylglucosamine residues in two types of disaccharide units that are antigenically distinct (Kabat et al., 1982; Gooi et al., 1983a) and termed type 1, Gala1 -+3GlcNAc, and type 2, Galpl-+4GlcNAc (Watkins, 1980). This region is extremely varied in length and branching pattern (Hounsell & Feizi, 1982)and its antigenicity varies accordingly. In linear sequence the disaccharides are joined by 1-+3 linkage as in structures (X) and (XI), and branched structures are formed by the addition of 1 -+6-linked disaccharide units as in structures (VIj(1X). The short, type-2 branch point sequences (broken underlining), as in structures (V1)-(IX), express the antigenic determinant recognized by a group of human monoclonal antibodies, designated anti-I group 1, among which anti-I Ma is the best characterized (Feizi, 1981~).Long and branched type-2 sequences such as structures (VII) and (IX) express the antigenic determinants (solid underlining) 592 zyxwvutsrq zyxwvutsr zyxwvutsr zyxwv zyxwvu BIOCHEMICAL SOCIETY TRANSACTIONS recognized by a second group of human monoclonal antibodies, designated anti-I group 2. These include anti-I Step and anti-I Low (Feizi et al., 1979; K. Uemura, T. Feizi, R. A. Childs, M. Kordowicz & P. Hanfland, unpublished work; H. C. Gooi, A. Veyritres, P. Scudder, E. F. Hounsell & T. Feizi, unpublished work). Long-chain linear structures consisting of repeating type-2 sequences, as in structure (X),express the i antigenic determinant recognized by anti-i Den (Niemann et al., 1978; Uemura et al., 1983; H. C. Gooi, A. Veyritres, P. Scudder, E. F. Hounsell & T. Feizi, unpublished work), whereas the linear type-Ibased structure (XI) is recognized by the human Waldenstrom macroglobulin IgMWoo (Kabat er al., 1982) and the mouse hybridoma antibody FC 10.2 (Gooi et al., 1983~). Exclusively type-1 based peripheral region antigens Lea Galfi1+3GlcNAc. t 1.4 .. Fucu Galfi1+3GlcNAc.. Leb tl,2 t1.4 Fucu Fuca Galfi1+3GlcNAc.. 19.9 t2.3 . . t1.4 NeuAcu Fucu zyxwvutsrqp Anti-I Ma and PNL Galfil f - Anti-I Group 1 .a Anti-I Groups 1 and 2 ’* Galfil+4GlcNAcfiI ~Galfil+4GlcNAcfil+3Galfil+4GlcNAc.. . f -- - - - - -- - - - - - - - - -- - - -.> Galfil+4GlcNAcfil * ~~Galfi1+4GlcNAcf .. ...................... -*4 ~Galfi1+4GlcNAcfil/f Galfil+4GlcNAcfil Anti-I Groups 1 and 2 Galfil+4GlcNAcfil Anti-i f Galfi1+4GlcNAcfi1+3Galfi1+4GlcNAcfi1+3Galfil+4GlcNAc.. . Galfil+3GlcNAcfi1+3Galfi1+4GlcNAc.. . IgMWm FC 10.2 Although oligosaccharides (VIIHXI) have not yet been isolated and sequenced from mUCUS glycoproteins, they are presumed to occur in a number of gastrointestinal mucins, e.g. gastric mucins of sheep (Wood et al., 1980, 1981) and of man (Picard & Feizi, 1983, 1984), and human ovarian cyst glycoproteins (Wood et al., 1979; Gooi et al., 1983a), based on immunochemical analyses. The carbohydrate sequence of structure (VII) was deduced to be a common backbone structure in ovarian cyst mucins (Lloyd & Kabat, 1968) and in human gastric mucins (Oates et al., 1974) on the basis of structural i~folmation on partially degraded Oligosaccharides. Peripheralregions. Among the structures in the Peripheral regions, the best characterized are the major blood group antigens H, A, B, Lea and Leb shown below. Type-1 or -2 based peripheral region antigens H Galfi1+3/4GlcNAc. . t 1.2 Fucu A GalNAcul+3Galj?1+3/4GlcNAc. t 1.2 . Fucu B (XI Gala1 +3Gal/31+3/4GlcNAc. . t1.2 Fucu (XI) Exclusively typ-2 based peripheral region antigens Galfi1+4GlcNAc. . . fiE;:en) tl.3 Fucu c14 (yhapten) Galfil+4GlcNAc. . . tl,2 tl.3 Fuca Fucu Whereas the H, A and B antigens occur on both type-1 and type-2 backbones, the Lea and Leb antigens are based exclusively on type-1 backbone structures (Watkins, 1980). The structural elucidation of these antigens was achieved by the classical studies of Moraan. Watkins. Kabat and their colleagues (reviewed by Waikins, 1980; Kabat, 1982) using mucin-type glycoproteins, in particular, ovarian cyst glycoproteins, as sources of antigenically active oligosaccharides. In recent years the same glycoproteins have been invaluable in the structural eludication of a number of hybridomadefined antigens which behave as tumour-associated or differentiation antigens of man or mouse (Feizi, 19816, 19836,1984). Our studies have shown that mucins are a rich source of carbohydrate structures which occur as membrane-associated antigens recognized by hybridoma antibodies. Thus, the stage-specific embryonic antigen of mouse, recognized by the hybridoma antibody anti-SSEA-1, consists of a trisaccharide sequence [a1 +3 fucosylated type1984 zyxwvutsrqp zyxwvutsrq zyxwvu zyx zyxwvu zyxwvuts zyx zyxwvu 607th MEETING, LONDON 593 2 chain (Gooi et al., 1981; Hounsell et al., 1981)], and the colon tumour-associated antigen of man, recognized by hybridoma antibody C14, is a tetrasaccharide sequence [a1+ 2 and a1 +4 difucosylated type-2 chain (Brown et al., 1983)], both of which were already known to occur as peripheral structures of ovarian cyst glycoproteins from the structural studies of Lloyd et al. (1968) and were designated X-hapten and Y-hapten respectively (Hakomori & Kobata, 1974). Furthermore, the same carbohydrate structures may have a different ‘marker’ role in different animal species. Our studies of the hybridoma antibodies VEP8 and VEP9, which were raised against the human promyelocytic cell line HL60, have shown that both antibodies, like anti-SSEA-1, react strongly with ovarian cyst mucins derived from nonsecrZtors and recognize a1 +3-fucosylated type-2 chains (Feizi, 19830, Gooi et al., 19836). This determinant behaves as a myeloid cell-specific antigen among blood cells of man but not those of mouse (S. J. Thorpe, 1982 cited by Feizi, 1983~).Another peripheral structure which behaves as a tumour-associated antigen in the human colon is a 2 4 3sialylated Lea structure, recognized by the hybridoma antibody 19.9 (Magnani et al., 1982; Hansson et al., 1983). This antigen was originally described on glycolipids but is also expressed on gastrointestinal mucins as discussed below. Monoclonal antibodies in the structural characterization of mucin-type glycoproteins Since the carbohydrate chains of mucin-type glycoproteins are so heterogeneous and difficult to purify, and the amounts available are often too small for detailed structural characterization, we have used well-characterized monoclonal antibodies as reagents in studies of the carbohydrate chains of membrane-associated glycoproteins of mucin type, as well as those of epithelial mucins. Thus, anti-I and -i antibodies have revealed the presence of linear and branched poly-N-acetyl-lactosamine sequences in mucintype carbohydrate chains of the high molecular weight glycoproteins of B lymphocytes known as ‘T 200’ glyco- proteins (Childs & Feizi, 1981; Childs et a f . , 1983a). In addition there is evidence that the sialoglycoprotein GP-2 of bovine erythrocyte membranes (Suzuki et al., 1983) is rich in 0-linked oligosaccharides with branched poly-N-acetyllactosamine backbones such as structures (VIII) and (IX) (Y. Suzuki, H. C. Gooi and T. Feizi, cited by Loomes et al., 1984). Although the native GP-2 has negligible Ii antigen activities, the mild-acid-treated glycoprotein is a most potent inhibitor of anti-I antibodies of groups 1 and 2. We have obtained structural information on gastrointestinal mucins also by using well-characterized antibodies. Together with PNL and conventional anti-H, Lea and Leb reagents, the monoclonal antibodies anti-I Ma, FC 10.2 and 19.9 have been invaluable in showing ( a ) marked differences in the carbohydrate chains of mucins derived from the human stomach and distal colon and ( b ) the changes that occur in neoplasia. These observations are summarized below. Antigenic markers of the glycoproteins of non-neoplastic mucosae and of tumours of the stomach and distal colon. In studies which have been described in part by Picard et al. (1978), and Picard & Feizi (1983, 1984) and others which will be described in detail elsewhere, we have used the PNL, anti-I Ma, FC 10.2, 19.9, anti-H, anti-Lea and anti-Leb antibodies to study the expression of their corresponding antigens in paired glycoprotein extracts from the non-neoplastic mucosae and the tumours of patients with carcinoma of the stomach and of the distal colon. The secretor status of the patients was determined by examination of their saliva for A, B and H antigen content (Picard et al., 1978). ( a ) Glycoprotein extracts of stomach. In the glycoprotein extracts of non-neoplastic mucosae of secretors, the blood group H and Leb antigens are strongly expressed (Table 1). As is well known, these two antigens are lacking or they are found in very low levels in the extracts from non-secretors (for reviews see Watkins, 1980; Hounsell & Feizi, 1982). In non-secretors, antigens associated with exposed or unsubstituted core regions (PNL receptor) and backbone regions (I Ma and FC 10.2) are strongly expressed (Table 1). Table 1. Expression of the PNL receptor and of the carbohydrate antigens IMa, Fc 10.2, Le”, 19.9, H , and W , in paired glycoprotein extractsjrom non-neoplasticmucosae and tumours ojpatients oj’knownsecretor status with carcinoma of the stomach and of the distal colon. Abbreviations : N, non-neoplastic mucosae; T, tumour; + , antigen commcnly detected; ( + ), antigen occasionally detected; @, antigen detected among tumour extracts only; f,antigen present in tumour extracts of some individuals but deleted in those of others. zyx zyxwvutsr Stomach Distal colon \ Secretors PNL Designation and structure GalP+3GalNAc I Ma Galb-+4GlcNAcj I 6 FC 10.2 GalP+ 3GlcNAcb-t 3Gal~-+4GlcNAc Lea Galb-+3GlcNAc Non-secretors T T 0 0 N + + + 0 8 + + + + 8 + + I Secretors A ‘N T’ Non-secretors N T + (+I + * + + TI. 4 Fucu 19.9 Gal/l-+3GlcNAc 12. 3 0 TI. 4 NeuAcu Fuca H Galfi-+3/4GlcNAc k 0 f 0 TI, 2 Fucu Leb GalP-+3GlcNAc TI, 2 Fucu Vol. 12 TI. 4 Fucu 8 594 BIOCHEMICAL SOCIETY TRANSACTIONS zyxwvu zyxwv zyxwvuts zyxwvutsrqp zyxwv In addition the Lea and 19.9 antigens are normally backbone structures such as I, i and FC 10.2, are due to (a) expressed in the gastric mucosal glycoproteins of non- the predominance of short carbohydrate chains in the secretors. colorectal mucins or (b)the presence of substituents such as On the other hand, when gastric cancers arise in sulphate residues which are known to occur in these mucins secretors, the five antigens that are normally prominent in and may mask the antigenicity of long chain structures. non-secretors appear as tumour-associated antigens (Table Demonstration of the carbohydrate antigens on high I). As is well known from the early work of Oh-Uti (1949) molecular weight glycoproteins. The antigenic analyses and numerous subsequent studies (reviewed by Feizi, 1982) described above were carried out by quantitative prethe H, A and B antigens may diminish and even disappear cipitation or haemagglutination inhibition (Picard et al., in the glycoprotein extracts of secretors. The five antigens 1978; Picard & Feizi, 1983) or by solid-phase radionormally expressed in the extracts of non-secretors usually immunoassay (Picard & Feizi, 1984) in which glycopersist at high levels in extracts from the corresponding protein-rich extracts of epithelium or of tumours were used tumours (Picard et al., 1978; J. K. Picard & T. Feizi, as inhibitors of the binding of monoclonal antibodies to unpublished work). reference glycoproteins. In order to identify the carrier The biochemical basis of the tumour-associated changes molecules of the carbohydrate antigens, immunostaining of in these carbohydrate structures needs investigation. The ‘Western blots’ of the gastric and colonic glycoproteins diminished expression of the H and Leb antigens in the derived from normal and neoplastic mucosae have been tumours of secretors together with increased expression of carried out (Fig. 2) using the procedures described antigens associated with their precursors, are likely to be previously (Childs et al., 19836). These studies have due to incomplete biosynthesis of the blood group chains confirmed that the FC 10.2, 19.9 and I Ma antigens are (Hakomori & Young, 1978). However, the observations expressed on diffusely migrating high molecular weight with 19.9 antigen show that there also occurs anomalous glycoproteins, a large proportion of which barely enter the sialylation of blood group chains in the tumour tissues of 4-1 5% polyacrylamide gradient gels. These are charactersecretors. It will be of interest to establish whether the istic properties of highly glycosylated macromolecules such normal expression of 19.9 antigen in non-secretors and the as mucins and proteoglycans. anomalous expression in tumours of secretors is due to a lack of competition from the blood group H enzymes Speculations on the roles of the carbohydrate structures as (fucosyltransferase) or due to the presence of high levels of receptors We have briefly reviewed knowledge on the structures of the galactosyl a2-r 3 sialyltransferase. From these studies we conclude that the PNL, FC 10.2 carbohydrate moieties of mucin-type glycoproteins with and 19.9 determinants are normal antigens in the gastric particular reference to the recent observations that these mucosae of non-secretors (25% of the population are non- carbohydrate chains express a considerable number of secretors) but they are tumour-associated antigens in 75% of differentiation and tumour-associated antigens recognized the population who are secretors. None of the seven by monoclonal antibodies. The roles of these diverse antigens studied behaves as a tumour marker in the stomach antigens/structures, which are shared by a number of glycoproteins and glycolipids of the cell surface, will be the of non-secretors. (b) Glycoprotein extracts of distal colon. The antigen subject of future investigations. And these will be markedly patterns of glycoprotein extracts of the distal colon differ helped by the availability of well-characterized monoclonal considerably from those of the stomach. The antigens they antibodies. In conclusion, we would like to mention some express are usually those associated with short type-I recent observations which we believe are bringing us closer backbone structures. Irrespective of secretor status, Lea is to an understanding of the roles of the blood-group-related the dominant antigen in the glycoproteins from non-neo- family of carbohydrate structures as components of receptor plastic mucosae of the distal-colon (Picard & Feizi, 1983) systems. Monoclonal antibodies to the receptor for epidermal growth and FC 10.2 is occasionally detected (Table 1). As is well known (Szulman, 1966) the H and Leb antigens are lacking factor recognize blood group antigens. Two independent in this region of the large bowel even in secretors. However, observations on two monoclonal antibodies raised against the two latter antigens appear as tumour-associated the receptor for epidermal growth factor of the epidermoid antigens in the distal colon of secretors (Table 1). This was carcinoma cell line A431 have shown that their specificities first described by Denk et al. (1974) and it is thought to involve the blood group antigens. In one case the antigen represent a return to a foetal-like state. The distal colon of has been shown to be the type-1 blood group H structure the foetus has been found to express the blood group H, A (Fredman et al., 1983) and in the other, the blood group A This latter antibody, TL5, is of and B antigens until about the time of birth (Szulman, structure (Gooi etal., 1983~). special interest. Apparently it binds to a site on the glyco1966). We have observed that the 19.9 antigen appears as a protein receptor that is distinct from the growth-factortumour-associated antigen in glycoprotein extracts of the binding site. However, it has been reported (Schreiber et al., 1983) that when this antibody reacts with human foreskin distal colon in approximately half of the patients with carcinoma (Table 1). This is in agreement with immuno- fibroblasts and is then cross-linked with anti-mouse cytochemical observations (Arends et al., 1983) and with antibodies, the fibroblasts are stimulated to take up tritiated studies of glycolipid extracts of colon tumours (Hansson ef thymidine. If it can be confirmed that this effect is a result al., 1983). Thus 19.9 is an example of an antigen which is a of cross-linking the blood group A-active carbohydrate normal component in certain tissues of certain individuals chains of the epidermal growth factor receptor, this can be and a tumour-associated antigen in others, and whose taken as evidence that these saccharides are somehow involved in growth regulation. expression is greatly effected by the secretor gene. Galactose-binding tissue lpctin reacts preferentially with IiThe type-2 based antigens I and i are usually lacking in glycoprotein extracts of the normal mucosae and in primary active mucins. A widely distributed animal lectin, galactosecancers of the distal colon (Picard & Feizi, 1983). These are binding protein (Barondes, 1981), has been shown to react expressed in a proportion of extracts from metastatic colon with Ii-active ovarian cyst glycoproteins in preference to tumours (Feizi et al., 1975; J. K. Picard & T. Feizi, un- those lacking these activities (Childs & Feizi, 1979). The published work). Structural studies are awaited to establish same lectin has been found to stimulate in vitro the reactivity whether the lack of antigens associated with long chain of sialyltransferase of bovine milk (Scudder et al., 1983). 1984 zy zyxwvutsrqpon 595 607th MEETING, LONDON (a) Ma 19 Fc T N T N T Nm N T Nh N T fb) N 19 T Fc N Nrn T N 0- 200- 94- 68- zyxwvutsrq zyxwvutsr zyxwvuts Fig. 2. Immunostaining with anti-carbohydrate antibodies and radioautography of glycoprotein extracts from stomach (a) and distal colon (b) of a patient (non-secretor) with gastric cancer and a patient (secretor) with cancer of the distal colon respectively ( R . A . Childs, unpublished work) The extracts (Picard & Feizi, 1984) were reduced with 2-mercaptoethanol, boiled in 2% sodium dodecyl sulphate, electrophoresed in 4-1 5% polyacrylamide gradient gels, transferred on to nitrocellulose paper and incubated with antibodies. Bound mouse and human antibodies were detected by using * 251-labelledanti-mouse and anti-human immunoglobulins as described previously (Childs et al., 1983b). Abbreviations : N, T, extracts from non-neoplastic mucosae and tumours, respectively; FC, hybridoma antibody FC10.2; 19, hybridoma antibody 19.9; Ma, anti-I Ma; Nm and Nh, normal mouse and human serum respectively. However, the precise role of the lectin is far from clear. On the other hand, evidence is accumulating on the roles of this family of carbohydrate chains as receptors for infective agents, as discussed below. Host-cell receptors for Mycoplasma pneumoniae are sialylated oligosaccharides of Ii-antigen type on 0- and N-linked oligosaccharides and glycolipids. We have recently observed that the host-cell receptors for the human pathogen Mycoplasma pneumoniae are long-chain oligosaccharides with sialic acid joined by a2+3 linkage to the terminal galactose residues of poly-N-acetyl-lactosamine sequences of 11-antigen type. These structures may be carried on mucin-type chains as in GP-2 of bovine erythrocyte membranes, as well as the N-linked chains of band 3 protein (Loomes et al., 1984) and glycolipids of erythrocyte membranes (Uemura and coworkers, cited by Loomes et al., 1984). Although the information is less complete, there are indications that sialylated oligosaccharides of poly-Nacetyl-lactosamine type and their asialo forms may be receptors for the a-toxin of Staphylococcus aereus (Kato & Naiki, 1976), the haemagglutinin of Sendai virus (Suzuki et al., 1983) and for Streptococcus pneumoniae, respectively (Anderson et al., 1983). These observations raise the possibility that receptor systems for infective agents may consist of constellations of glycoproteins and glycolipids with similar carbohydrate structures. Vol. 12 Summary In this report the carbohydrate antigens expressed on the three oligosaccharide domains, core, backbone and peripheral, of mucin-type glycoproteins are briefly reviewed in the light of recent observations with monoclonal antibodies. These have revealed that a number of cell-surface antigens which behave as tumour-associated and differentiation antigens of man or mouse are abundantly expressed on the carbohydrate chains of a variety of secreted mucins of human and animal origins and they belong to an antigen system which also includes the major blood group antigens. Examples are given of the use of well-characterized anticarbohydrate antibodies to derive structural information on ( a ) mucin-type glycoproteins of human 3 lymphocyte membranes, (b) the high molecular weight glycoproteins of the normal human gastric and distal-colon mucosae and (c) tumour-derived glycoproteins from these two organs. Major differences between the antigenicities of the normal stomach and distal-coton, and between their tumourderived glycoproteins, and the important effect of the secretor status in the expression of these antigens are described. These observations have enabled a better understanding of the individual and tissue differences in the expression of tumour-associated antigens. The possibility is raised that these carbohydrate structures (many of which also occur on certain N-linked oligosaccharides and zyx zy 596 BIOCHEMICAL SOCIETY TRANSACTIONS glycolipids) are components of receptor systems for endogenous ligands. More tangible evidence is cited for the role of certain structures in this family of saccharides as receptors for infective agents. H. C. G. is supported by the Arthritis and Rheumatism Council. L. M. L. is holder of a Ph.D. studentship from the Medical Research Council. S. J. T. is supported by the Cancer Research Campaign and K. 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Res. 90, 269-282 zyxwvutsrqp zyxwvutsrq zyxwvuts zyxwvutsrq Andersson, B., Dahmen J., Frejd, T., Leffler, H., Magnusson, G., Noori, G. & Svanborg Eden, C. (1983) J . Exp. Med. 158, 559570 Arends, J. W., Wiggers, T., Schutte, B., Thijs, C. T., Verstijnen, C., Hilgers, J., Blijham, G. H. & Bosman, F. T. (1983) Int. J. Cancer 32, 289-293 Barondes, S . (1981) Ann. Rev. Bwchem. 50, 207-231 Brown, A., Feizi, T., Gooi, H. C., Embleton, M. J., Picard, J. K. & Baldwin, R. W. (1983) Bwsci. Rep. 3, 163-170 Childs, R. A. & Feizi, T. (1979) FEBS. Lett. 99, 175-179 Childs, R. A. & Feizi, T. (1981) Biochem. Biophys. Res. Commun. 102, 1158-1164 Childs, R. A., Dalchau, R., Scudder, P., Hounsell, E. F., Fabre, J. W. & Feizi, T. (1983~)Biochem. Biophys. Res. Commun. 110, 424-43 1 Childs, R. A., Pennington, J., Uemura, K., Scudder, P., Goodfellow, P. N., Evans, M. J. & Feizi, T. (19836) Biochem. J. 215, 491-503 Denk, H., Tappeiner, G . , Davidovits, A,, Eckerstorfer, R. & Holzner, J. H. (1974) J. Natl. Cancer Inst. 53, 933-942 Feizi, T. (1981~)Immunol. Commun. 10, 127-156 Feizi, T. (19816) Trends Biochem. Sci. 6, 333-335 Feizi, T. (1982) Med. Biol. 60, 7-11 Feizi, T. (1983~)Ci6a Found. Symp. Fetal Antigens Cancer %, 216221 Feizi, T. (19836) Biochem. SOC.Trans. 11, 263-265 Feizi, T. (1984) Biochem. SOC.Trans. 12, 545-549 Feizi, T., Tuberville, C. & Westwood, J. H. (1975) Lancet u, 391393 Feizi, T., Childs, R. A., Watanabe, K. & Hakomori, S. (1979) J. Exp. Med. 149, 975-980 Fredman, P., Richert, N. D., Magnani, J. L., Willingham, M. C., Pastan, I. &Ginsburg, V. (1983)J. Biol. Chem. 258,112061 1210 Gooi, H. C., Feizi, T., Kapadia, A., Knowles, B. B., Solter, D. & Evans, M. J. (1981) Nature (London) 292, 156158 Gooi, H. C., Williams, L. K., Uemura, K., Hounsell, E. F., McIlhinney, R. A. J. & Feizi, T. (1983~)Mol. Immunol. 30,607613 Gooi, H. C., Thorpe, S. J., Hounsell, E. F., Rumpold, H., Kraft, D., Forster, 0.& Feizi, T. (19836) Eur. J . Immunol. 13, 306312 Gooi, H. C., Schlessinger, J., Lax, I., Yarden, Y., Libermann, T. A. & Feizi, T. (1983~)Biosci. Rep. 3, 1045-1052 Hakomori, S. & Kobata, A. (1974) in The Antigens (Sela, M., ed.), pp. 8&122, Academic Press, New York zyxwvutsrq zyxwvutsr zyxwvutsrq The human blood-group-Sda determinant: a terminal non-reducing carbohydrate structure in N-linked and mucin-type glycoproteins linked oligosaccharide chains in glycoproteins. The Sid blood group system was first recognized by Renton et al. (1967) and Macvie et al. (1967) and has one antigen, Sda, which is inherited as a Mendelian dominant character. The erythrocytes of about 92% of individuals carry the Sd" antigen; of the remaining 8% about half lack detectable Sda The human blood-group-Sd"determinant is a carbohydrate activity on their erythrocytes but do not have Sda antibodies structure which may be carried on both N-linked and 0- in their sera whereas the other 4% lack the antigen on their erythrocytes and have anti-Sd" in their sera. Amongst Sda(+) individuals considerable variations are observed in Abbreviation used: T-H, Tamm-Horsfall. A. S. R. DONALD, A. D. YATES, C. P. C. SOH, W. T. J. MORGAN and W. W. WATKINS Division of Immunochemical Genetics, MRC Clinical Research Centre, Warford Road, Harrow, Middx. HA I 3UJ, U . K . 1984