The principal focus of our research is the characterization of human CD8+ effector cell functional activities in the context of both antiviral and antitumor associated antigen (TAA) responses. Many of these studies examine cytotoxic T-lymphocyte (CTL) reactivities existent in AIDS and cancer patients. We have developed in vitro model systems for antigen-specific CTL precursor (CTLp) activation and expansion as a means of evaluating immune-based strategies of potential therapeutic utility. Central to these efforts is the use of recombinant poxvirus transient expression vectors. An extensive panel of these constructs expressing various viral, cytokine, TAA, and accessory molecule genes is employed in these studies. Of particular interest are canarypox vector constructs, which are pancytotropic for mammalian cells but do not result in productive infection and accompanying cellular cytopathology.
In recent studies we have begun to examine anti-HIV-1 CTL responses to candidate AIDS vaccines being tested in Phase I clinical trials. Whereas 1st generation envelope subunit immunogens failed to elicit demonstrable CTL reactivities, new strategies involving vector priming and subunit boosting have reproducibly produced CTL responses in 40-65% of vaccinees. Currently, CTL clones are being established so that MHC-restricting elements can be identified and target epitopes can be mapped. We have developed an HIV-1-based targeting strategy for measurement of vaccinee CTL and have found broad CTL specificities against autologous CD4+ lymphocyte targets infected with genetically diverse HIV-1 isolates representing numerous viral clades. Thus, clade B-based vaccines can elicit significant cross-clade CTL reactivities that are restricted by MHC class I allelic expression within the population.
Our studies of CD8+ effector-cell function in HIV-1-infected patients have involved analyses of both cytolytic and noncytolytic mechanisms of viral suppression. The latter phenomenon has been shown to be mediated in part by the -chemokines RANTES, MIP-1, and MIP-1. Using CD8+ clones derived from infected patients, we have shown that CTL activity and noncytolytic viral suppression are separate and distinct activities, although not mutually exclusive. Whether similar cellular reactivities accompany other viral infections is the focus for future planned studies. To better delineate the correlates of immune protection in HIV-1 infection, we are presently attempting to characterize CD8+ effector-cell functions in a cohort of long-term nonprogressors (LTNP) as well as a cohort of patients with rapidly progressing disease. By comprehensive assessment of cytotolytic and noncytolytic effector function at these 2 disease extremes, we hope to gain insights into the relative contribution each can make with regard to control of virus-induced immunopathogenesis. Likewise, we have also begun to examine cellular anti-HIV-1 reactivities in a cohort of 15 highly exposed/uninfected women in order to identify possible correlates in immune protection. Complementary studies are also being conducted with a cohort of acute HIV-1 seroconvertors from Port-of-Spain, Trinidad.
Last, we are intensively investigating anti-TAA CD8+ CTL reactivities present in patients with malignant melanoma, breast cancer, ovarian cancer, and pancreatic carcinoma. We have demonstrated the presence of MAGE-1 specific CTLp in the tumor-infiltrating lymphocytes (TIL) of a MAGE-1 expressing breast tumor, thus confirming that a patient can mount a cytolytic response to conserved TAA expressed by their growing tumor. Extensive characterization of TAA-specific effectors present in association with various human malignancies is among the future goals of this project. Most important, these studies will provide a framework for cancer vaccine strategies aimed at augmenting existent anti-TAA reactivities in patients. Once again, poxvirus/TAA vector constructs play a central role in the development of these treatment strategies. TAA targets of interest include MAGE-1, MAGE-3, BAGE, GAGE, HER2/neu, p53, and k-ras.
Ferrari GF, Humphrey W, McElrath MJ, Excler J-L, Duliege A-M, Clements ML, Corey LC, Bolognesi DP, Weinhold KJ. Clade B-based HIV-1 vaccines elicit cross-clade CTL reactivities in uninfected volunteers. Proc Natl Acad Sci USA 1997;94:1396-1401.
Greenberg ML, Lacey SF, Chen CH, Bolognesi DP, Weinhold KJ. Noncytolytic CD8 T cell-mediated suppression of HIV replication. Springer Semin Immunopathol 1997;18(3):355-69.
Toso JF, Oei C, Oshidari F, Tartaglia J, Paoletti, E, Lyerly, HK, Talib S, Boon T, Weinhold KJ. MAGE-1 specific CTLp present among tumor infiltrating lymphocytes from a patient with breast cancer: characterization and antigen-specific activation. Cancer Res 1996;56:16-20.
Ahearne PM, Morgan RA, Sebastian MW, Bolognesi DP, Weinhold KJ. Multiple CTL specificities against autologous HIV-1 infected BLCLs. Cell Immunol 1995;161:34-41.
Egan MA, Pavlat WA, Tartaglia J, Paoletti E, Weinhold KJ, Clements ML, Siliciano RF. Induction of human immunodeficiency virus type 1 (HIV-1)-specific cytolytic T lymphocyte responses in seronegative adults by a nonreplicating, host-range-restricted canarypox vector (ALVAC) carrying the HIV-1MN env gene. J Infect Dis 1995;171:1623-7.
Ferrari G, King K, Rathbun K, Packard MV, Bartlett JA, Bolognesi DP, Weinhold KJ. Interleukin 7 (IL 7) enhancement of antigen-driven activation/expansion of human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T-lymphocyte precursors (CTLp). Clin Exp Immunol 1995;101:239-48.
Toso JF, Chen CH, Mohr JR, Piglia L, Oei C, Ferrari G, Greenberg ML, Weinhold KJ. Oligoclonal CD8 lymphocytes from asymptomatic HIV-infected individuals inhibit HIV-1 replication. J Infect Dis 1995;172:964-73.
Ferrari G, Place CA, Ahearne PM, Arthur LO, Bolognesi DP, Weinhold KJ. Comparison of anti-HIV-1-ADCC reactivities in infected human and chimpanzees. J Acquir Immune Defic Syndr 1994;7(4):325-31.
Chen C-H, Weinhold KJ, Bartlett JA, Bolognesi DP Greenberg ML. CD8+ T-Lymphocyte-mediated inhibition of HIV-1 LTR transcription: a novel antiviral mechanism. AIDS Res Hum Retroviruses 1993;9(11):1079- 86.
Haynes BF, Arthur LA, Frost O, Matthewa TJ, Langlois AJ, Palker TJ, Hart MK, Scearce RM, Jones DM, McDanal C, and others. Conversion of an immunogenic human immunodeficiency virus (HIV) envelope synthetic peptide to a tolerogen in chimpanzees by the fuogenic domain of HIV gp41 envelope protein. J Exp Med 1993;177:717-27.