EVALUATION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 (HIV-1)-SPECIFIC CYTOTOXIC T-LYMPHOCYTE RESPONSES UTILIZING B-LYMPHOBLASTOID CELL-LINES TRANSDUCED WITH THE CD4 GENE AND INFECTED WITH HIV-1

Analysis of major histocompatibility complex-restricted cytotoxic T ly mphocytes (CTL) capable of killing human immunodeficiency virus type 1 (HIV-1)-infected targets is essential for elucidating the basis for H IV-1 disease progression and the potential efficacy of candidate vacci nes. The use of primary CD4(+) T cells with variable infectivity as ta rgets for such studies has significant limitations, and immortal autol ogous cells with high levels of CD4 expression that can be consistentl y infected with HIV-1 would be of much greater utility. Therefore, we transduced Epstein-Barr-virus-transformed B-lymphoblastoid cell lines (LCL) with a retroviral vector, LT4SN, containing the human CD4 gene. Stable LCL in which more than 95% of cells expressed membrane CD4 were obtained. Aliquots were infected with HIV-1, and, after 4 to 7 days, nearly all of the cells contained cytoplasmic gag and produced high le vels of p24 antigen. The ability of major histocompatibility complex-r estricted CD8(+) CTL to lyse such HIV-1-infected CD4-transduced LCL (L CL-CD4(HIV-1)) was evaluated. These autologous targets were lysed by C TL generated from an HIV-1-uninfected vaccinee over a broad range of e ffector-to-target ratios. Similarly, the LCL-CD4(HIV-1) were efficient ly lysed by fresh circulating CTL from HIV-1-infected individuals, as well as by CTL activated by in vitro stimulation. Both HIV-1 env- and gag-specific CTL effecters lysed LCL-CD4(HIV-1), consistent with the c ellular expression of both HIV-1 genes. The LCL-CD4(HIV) also function ed as stimulator cells, and thus are capable of amplifying CTL against multiple HIV-1 gene products in HIV-1-infected individuals. The abili ty to produce HIV-1-susceptible autologous immortalized cell lines tha t can be employed as target cells should enable a more detailed evalua tion of vaccine-induced CTL against both homologous and disparate HIV- 1 strains. Furthermore, the use of LCL-CD4(HIV-1) should facilitate th e analysis of the range of HIV-1 gene products recognized by CTL in se ropositive persons.