Activation and infection of B cells by Epstein-Barr virus. Role of calcium mobilization and of protein kinase C translocation.
Both the activation and the transformation of human B cells by EBV were inhibited by either the Ca2+ channel blocking agent verapamil or the combination of theophylline and dibutyryl cAMP: the day 4 and day 20 peaks of [3H]TdR incorporation were abolished; the EBNA marker was not expressed by day 10; lymphoblastoid cell lines did not arise. Short term incubation of B cells with EBV or verapamil showed that the effect of verapamil was reversible and took place early in the interaction between EBV and B cells. The effect of EBV on the early metabolic events of B cell response was thus examined in the presence and in the absence of the drugs. Compared to anti-mu stimulation, supernatant of the transforming B95-8 strain as well as that of the non-transforming P3HR1 strain induced a drug sensitive increase of the free cytosolic Ca2+ concentration. This increase was associated with a protein kinase C translocation from the cytosol to a membrane bound compartment. Moreover, B95-8 supernatant induced phosphatidyl inositol metabolism by human B cells but at least four times less than that induced by anti-mu antibody. These metabolic events induced by EBV were significantly inhibited by anti-CD21 antibodies whereas anti-mu induced metabolic events were not. The infection of EBV negative Ramos cell line was prevented by verapamil or by theophylline + dibutyryl cAMP. Verapamil did not modify the density of EBV receptors but negatively interfered with the penetration of the virus into B cells. Thus B cell activation through the EBV receptor and virus penetration share a common metabolic pathway which is also used for transduction of the signal delivered through the membrane Ig.
Dugas
B
B
Roussel-Uclaf, Département des Biotechnologies, Romainville, France.
Delfraissy
J F
JF
Calenda
A
A
Peuchmaur
M
M
Wallon
C
C
Rannou
M T
MT
Galanaud
P
P
D000888:Antibodies, Anti-Idiotypic; D001402:B-Lymphocytes / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D002472:Cell Transformation, Viral / Q000187:drug effects; D003600:Cytosol / Q000201:enzymology; D004854:Herpesvirus 4, Human / Q000187:drug effects / Q000648:ultrastructure; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D007295:Inositol Phosphates / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism* / Q000502:physiology; D014700:Verapamil / Q000494:pharmacology
D000888:Antibodies, Anti-Idiotypic; D007075:Immunoglobulin M; D007295:Inositol Phosphates; C044203:anti-IgM; D014700:Verapamil; D011493:Protein Kinase C; D002118:Calcium