Regulator genes affecting red cell antigens.
Several mechanisms may be involved to explain the action of genes that regulate the expression of red cell antigens. When carbohydrate antigens are involved, lack of an enzyme in the biochemical pathway prevents formation of the precursor for the next and following steps of that path, or, alternatively, addition of an extra sugar to the immuno-dominant sugar may produce a new structure in which the expression of the expected antigen is masked. Thinking of genetic rather than biochemical interference, a regulator gene may "switch-off" the action of a structural gene, and this mechanism could involve the upset of repressor and/or derepressor genes. The mechanisms for the regulator genes described in this article are unknown. The effect of XGR is limited to red cells: the expression of 12E7 antigen on other tissues and cells, other than red cells, is invariable. The reported effects of XOr and XQ are for red cells, but it is unlikely that other cells and tissues have been studied intensively; propositi with these regulator genes are much rarer than people informative for XGR and In(Lu). The effects of In(Lu) are not limited to red cells but have been shown to regulate the expression of p80 on some white cells. Most of the abnormalities in Rhnull cells appear to be associated with the lack of the Rh antigens and lack of Rh proteins. The hypothesis of a functional complex involving Rh, lack of which affects incorporation of apparently unrelated proteins into the red cell membrane, is an attractive idea. Studies of the similar phenotype, Rhmod, suggest that some Rh specificities can be present in cells that appear to be as abnormal, serologically and morphologically, as Rhnull cells. Perhaps some polypeptides are functionally more important than others and perhaps all polypeptides required for the functional efficiency of the Rh complex have not yet been identified. Lack of Lutheran antigens is not always accompanied by modification of other red cell antigens. As suggested by Telen and green, if In(Lu) acts via a single mechanism, then that mechanism differs from that of XS2. Certainly the mechanisms of In(Lu) and XS2 differ in their action on the expression of CD44 or p80 antigens. The red cell surface is well charted territory, familiar to serologists, immunologists, biochemists, and geneticists. It still provides an excellent model for study of cell surface antigens and for the regulator genes described above that modify expression of some red cell antigens.(ABSTRACT TRUNCATED AT 400 WORDS)
Tippett
P
P
Medical Research Council Blood Group Unit, London, England.
D000954:Antigens, Surface / Q000235:genetics*; D001789:Blood Group Antigens / Q000235:genetics*; D004912:Erythrocytes / Q000276:immunology*; D005260:Female; D005786:Gene Expression Regulation; D005796:Genes; D005799:Genes, Dominant; D005809:Genes, Regulator; D006031:Glycosylation; D006801:Humans; D008297:Male; D010641:Phenotype; D012150:Polymorphism, Restriction Fragment Length; D016201:Receptors, Lymphocyte Homing / Q000096:biosynthesis / Q000235:genetics*; D014960:X Chromosome
D000954:Antigens, Surface; D001789:Blood Group Antigens; D016201:Receptors, Lymphocyte Homing