CHARACTERIZATION OF THE EBV C3D RECEPTOR ON THE HUMAN JURKAT T-CELL LINE - EVIDENCE FOR A NOVEL TRANSCRIPT/

EBV is a human herpes virus that causes mononucleosis and is associate d with various tumors. EBV infects cells via the CR2 that was previous ly thought to be expressed only on the surface of B cells and certain epithelial cells. Recent findings in our laboratory and those of other s, however, have shown that the EBV receptor is also present on T cell s. Our study shows that Jurkat human T cells have a molecule that reac ts with both anti-CR2 antibodies and the third component of complement , C3. Furthermore, the data indicate that this molecule binds EBV dete cted by incubation with biotin-conjugated virus and streptavidin phyco erythrin. Viral binding is specific, as it is inhibited by nonconjugat ed virus, with anti-CR2 antibodies, and with an antibody reactive with the glycoprotein (gp350) that EBV uses to bind CR2. In addition, EBV variably infects Jurkat cells as demonstrated by the presence of trans cripts of Epstein Barr nuclear Ag (EBNA-1) using the polymerase chain reaction. Immunoprecipitation experiments with anti-CR2 antibodies and SDS-PAGE analysis reveal a protein with an apparent molecular mass of 155 kDa which is higher than the one seen in B cells. The size of thi s molecule is reduced to 119 kDa upon endoglycosidase F treatment. Nor thern blot analysis of Jurkat poly(A)+ RNA shows a transcript of 4.7 k b upon probing with the B cell CR2 cDNA. This size is consistent with that of B cell CR2 mRNA. Two cDNA clones were identified upon screenin g of a Jurkat cell cDNA library with the B cell CR2 cDNA. One of the c lones possesses an identical nucleotide sequence to the one correspond ing to B cell CR2, whereas the other represents a differentially splic ed transcript which lacks the exon 8b of B cell CR2. Analysis of Jurka t and Raji mRNA by PCR demonstrated the presence of this novel splice variant in both cell lines.