THE EPSTEIN-BARR VIRUS (EBV) MAJOR ENVELOPE GLYCOPROTEIN gp350/220-SPECIFIC ANTIBODY REACTIVITIES IN THE SERA OF PATIENTS WITH DIFFERENT EBV-ASSOCIATED DISEASES Jingwu XU 1 , Ali AHMAD 1 , Marie BLAGDON 1 , Mario D’ADDARIO 1 , James F. JONES 2 , Riccardo DOLCETTI 3 , Emanuela V ACCHER 3 , U. PRASAD 4 and Jose ´MENEZES 1 * 1 Laboratory of Immunovirology, Department of Microbiology and Immunology and Pediatric Research Center, University of Montreal and Ste-Justine Hospital, Montreal, Quebec, Canada 2 Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO, USA 3 Divisions of Experimental and Medical Oncology and AIDS, Centro di Riferimento Oncologico Aviano (PN) Italy 4 Department of Otorhinolaryngology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia gp350 of Epstein-Barr virus(EBV) inducesa strong immune response in EBV-infected individuals, but relatively little is known about the clinical relevance of thisresponse in patients with different EBV-associated malignancies and other dis- eases. Using our gp350-expressing cell clones, we studied gp350-specific humoral immune responses in the sera of individuals with nasopharyngeal carcinoma (N PC), chronic symptomatic EBV infection (CEI), Hodgkin’s disease (HD), acut e infectious mononucleosis (IM) and healthy EBV- seropositive individuals (HI). The titres of antibody-depen- dent cellular cytotoxicity (ADCC) antibodies were highest in H I followed by CEI, H D and N PC. EBV-neutralizing (N A) and gp350-specific IgG antibody profiles in these conditions were: CEI G HI G N PC G H D, whereas IgA titres were the highest in NPC sera followed by CEI and HD. The sera from IM patients were found to be negative for gp350-specific ADCC and IgA activities. Sera from HI were also negative for gp350-specific IgA. A significant positive correlation was found between serum gp350 IgA and viral capsid antigen IgA and a significant negative one between IgM and ADCC titres. High IgA titres were also found in CEI and EBV-genome positive HD in addition to N PC. Importantly, gp350-specific IgA titres were of prognostic value in N PC patients. O ur data provide new insights about the clinical relevance of gp350- specific immune responses in these diseases. Int. J. Cancer (Pred. Oncol.) 79:481–486, 1998.  1998 Wiley-Liss, Inc. Epstein-Barr virus (EBV) is a ubiquitous herpesvirus that infects more than 90% of humans world-wide. Primary infections usually occur in childhood and are asymptomatic. In developed countries where these infections are often delayed until adolescence, they cause infectious mononucleosis (IM) or glandular fever, which is normally a self-limiting lymphoproliferative disorder (Henle et al., 1968; reviewed in Rickinson and Kieff, 1996). Some cases of primary EBV infection, especially in individuals with X-linked lymphoproliferative syndrome, may be fatal (Purtilo, 1976). In some individuals, EBV infections produce unusually severe symp- toms which may last several years. Such infections are called severe chronic active or persistent EBV infections (reviewed in Okano et al., 1991; Rickinson and Kieff, 1996; Mayer et al., 1993). Primary EBV infections are believed to occur through epithelial cells of the oropharynx in which the virus undergoes the lytic cycle of replication and then infects B cells which become latently infected. Individuals, once infected, become carriers for life and may shed virus in saliva. EBV was the first human DNA virus to be recognized to have oncogenic potential. In vitro, it infects human B cells and immortalizes these into continuously growing cell lines (Pope et al., 1968; Menezes et al., 1976). EBV has been found associated with various human malignancies, e.g., endemic Bur- kitt’s lymphoma (BL), undifferentiated and poorly differentiated nasopharyngeal carcinoma (NPC), salivary gland tumors, Hodgkin’s lymphoma or disease (HD), B cell lymphomas in AIDS and organ transplant patients (reviewed in Rickinson and Kieff, 1996). The list of EBV-associated malignancies is ever-increasing; T cell lymphoma and NK cell lymphomas have been added to this list (Zhou et al., 1994; Kanavaros et al., 1996). A review of the characteristics and clinical symptoms of various EBV-associated disease conditions has been published by Rickinson and Kieff (1996). EBV induces a strong humoral and cellular immune response in infected individuals. These responses have been detected against both the latent and lytic cycle antigens of EBV (reviewed in Kanavaros et al., 1996). It is by virtue of this strong immune response that the virus replication is kept under control in normal healthy individuals. Immunodeficiency states and unidentified co-factors may precipitate uncontrolled EBV replication and/or EBV-associated diseases. In view of its association with various malignancies and other disease conditions, and the strong immuno- genicity of EBV antigens, anti-EBV vaccines have been developed and are under different phases of clinical trials (reviewed in Rickinson and Kieff, 1996; Khanna et al., 1995). These vaccines are based upon the major envelope glycoprotein of EBV, gp350/ 220 (hereafter referred to as gp350). Gp350 is the glycoprotein found most abundantly on the surface of EB virions as well as on the surface of EBV-infected cells in which EBV is lytically replicating (Pearson and Qualtie `re, 1978). It is the glycoprotein of the virion that binds to the EBV receptor CD21 (or complement receptor type II, CR2) and initiates infection (Tanner et al., 1987; Nemerow et al., 1985). gp350 is highly immunogenic and protects cotton-top tamarins against EBV-induced lymphomas when used as vaccine (Epstein et al., 1985; Morgan, 1992). gp350 is an important target protein at which host immune responses are directed. Monoclonal antibodies (MAbs) against gp350 inhibit EBV infection, and most of the EBV-neutralizing activity in EBV-seropositive individuals is gp350 specific (de Schryver et al., 1974; Hoffman et al., 1980; Thorley-Lawson and Geilinger, 1980). However, few studies have ever examined the gp350-specific immune responses in EBV-associated diseases. For these disease conditions, serum antibody titres of other EBV antigen complexes, e.g., viral capsid antigen (VCA), early antigen of restricted or diffuse type (EA-R or -D, respectively) and EBV nuclear antigen (EBNA), have been widely employed for diagnos- tic and prognostic purposes (reviewed in Okano et al., 1988). Lack of a suitable model for studying anti-gp350 immune responses in these EBV-associated diseases was a major deterrence in the past. However, to make such studies feasible, we developed permanent cell lines expressing gp350 and showed that these cell lines were Grant sponsors: Medical Research Council of Canada, J.L. Le ´vesque Foundation, Italian Association for Cancer Research and CNRP (project ACRO). *Correspondence to: Laboratory of Immunovirology, Ste-Justine Hospi- tal, 3175 Cote Ste-Catherine Rd., Montreal, Quebec, H3T 1C5, Canada. Fax: (514) 345–4801. E-mail: patenaude@justine.umontreal.ca Received 5 February 1998; Revised 16 April 1998 Int. J. Cancer (Pred. Oncol.): 79, 481–486 (1998)  1998 Wiley-Liss, Inc. Publication of the International Union Against Cancer Publication de l’Union Internationale Contre le Cancer