Red cell surface cysteine residue (285) of D polypeptide is not essential for D antigenicity.
BACKGROUND
Only one surface cysteine residue (285) has been thought to be involved in D antigenicity, according to studies using lyophilized or nonlyophilized red cell membranes. However, it has been reported that a 17-kDa chymotryptic fragment containing the N-terminus but not this cysteine residue is associated with D antigenicity.


METHODS
The role of the sulfhydryl (SH) group in D, c, and E antigenicity is assessed by using intact red cells treated with the reagents N-ethylmaleimide, 5,5'-dithiobis(2-nitrobenzoic acid), and 2-(4'-maleimidylanilino)- naphthalene-6-sulfonic acid. Antigenicity was appraised by hemagglutination titers and immunoprecipitation using human anti-D, -c, and -E.


RESULTS
Treatment with N-ethylmaleimide or 5,5'-dithiobis(2-nitrobenzoic acid) at various concentrations (< or = 5 mM) or for various times (< or = 120 min) did not cause significant decrease in hemagglutination titers as compared to untreated intact red cells. Moreover, immunoprecipitation of Rh antigen-carrying peptides by human anti-D was not affected by prior treatment with N-ethylmaleimide or 2-(4'maleimidylanilino)-naphthalene-6-sulfonic acid. Efficacy of blockage of SH groups was demonstrated by inhibition of palmitic acid uptake by the Rh polypeptides for prior treatment with N-ethylmaleimide and by the presence of fluorescent Rh polypeptides for prior treatment with 2-(4'maleimidylanilino)-naphthalene-6-sulfonic acid.


CONCLUSIONS
SH group involvement is not essential for D, c, or E antigenic expression in intact red cells.
Suyama
K
K
Cell Biochemistry Laboratory, Lindsley F. Kimball Research Institute, New York Blood Center, New York, USA.
Lunn
R
R
Goldstein
J
J
D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions; D003545:Cysteine / Q000737:chemistry; D005033:Ethylmaleimide / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D010168:Palmitates / Q000737:chemistry; D012204:Rh-Hr Blood-Group System / Q000276:immunology*; D013329:Structure-Activity Relationship; D013439:Sulfhydryl Reagents / Q000737:chemistry
D000911:Antibodies, Monoclonal; D010168:Palmitates; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen; D013439:Sulfhydryl Reagents; D003545:Cysteine; D005033:Ethylmaleimide