EXPRESSION ANALYSIS OF HUMAN RHESUS BLOOD-GROUP ANTIGENS BY GENE TRANSDUCTION INTO ERYTHROID AND NONERYTHROID CELLS

Rh blood group antigens are associated with non-glycosylated human ery throcyte membrane proteins encoded by two closely related genes, RHCE and RHD, and with a glycoprotein, a critical co-er;pressing factor enc oded by the RH50 gene. The sequence analysis of RHCE transcripts has r evealed that RhE/e and C/c serological phenotypes are associated with a nucleotide substitution in exon 5 and six substitutions in exons 1 a nd 2 of RHCE gene, respectively. Smythe et al, have shown that the ful l length transcript of RhcE gene expressed c and E antigens and the tr anscript of RhD gene expressed D and G antigens, using retroviral-medi ated gene transduction into K562 cells. We performed an epitope analys is of Rh antigen by constructing retroviral gene coding six RH cDNAs, which contain RhcE, ce, CE and D cDNAs, and CE-D, D-CE chimera cDNAs. The cDNAs were introduced into KU812E cells and the expressed antigens were analyzed by flow cytometry. These studies revealed that the C/c and E/e associated substitutions actually participated in respective p olymorphic epitopes. However, the C antigen was not detected on the KU 812E cells introduced with CE cDNA, despite E antigen being expressed. The study with the chimera gene between CE and D cDNAs also indicated that the Rh epitopes were not constructed with short polymorphic exof acial peptide loops only but also with other peptide fragments and mem brane components. Go-expression studies of Rh50 and RhD or cE gene in non-erythroid cells, 293, and expression studies of Rh50 in another er ythroid cell, HEL, did not show any Rh antigens on the transduced cell s, despite the Northern blot study showing both transcripts in the cel ls. It was suggested that at least a second co-expressing factor was n eeded to express RhCE or D antigens on the plasma membrane. (C) 1998 E lsevier Science Ireland Ltd. All rights reserved.