Immortalized cell lines derived from mice lacking both type I and type II IFN receptors unify some functions of immature and mature dendritic cells

Cells with dendritic morphology obtained from several organs of mice lackin g both type I and II IFN receptors were immortalized by a retrovirus and an alysed for their phenotype and for their function to induce cognate immune responses in vitro and in vivo. Two cell lines called AG101 (skin) and AG11 6 (brain) were cloned and analysed in more detail. They constitutively expr essed the cell surface markers CD45, CD11b, MHC class II, F4/80, N418, B7-2 and ICAM1 but were CD8- and B220-negative. Cells from both lines were capa ble of taking up ovalbumin (OVA). The processed protein was presented to th e OVA-specific T cell hybridoma BO97.105 which responded specifically with the production of IL-2. AG101 and AG116 cells were able to induce a mixed l ymphocyte reaction as shown by a 50-fold increase of IL-2 production over b ackground. Naive T cells were stimulated by antigen-primed AG101 and AG116, resulting in a T cell proliferation which was 20-30 times over background, and in IL-2 production it was 10 times the background. The capacity of AG1 01 or AG116 cells to prime naive T cells was directly compared with freshly isolated and cultured cutaneous dendritic cells (DC) from 129 Sv/Ev mice ( wtDC). After cognate T cell interaction, IL-6 (20-100-fold) and IL-12 p40 ( 100-1000-fold) were similarly upregulated in either AG101, AG116 or mature wtDC. To analyse the capacity of the immortalized DC to induce antibodies i n vivo, cell line AG116 was permanently infected with Borna disease virus ( BDV) which is unable to replicate in adult mice. One hundred and twenty-nin e Sv/Ev mice injected with different cell numbers of AG116 carrying BDV (bu t not control cells) produced antibodies against the viral BDVp40 and BDVp2 4 protein. Therefore, the cell lines AG101 and AG116 appear to unify some f unctions of immature and mature DC. They are able to pick up antigen and pr ocess it. In the absence of externally added cytokines, the antigen present ed on AG101 or AG116 cells drives T cells with an efficiency similar to mat ure DC. The cloned cell lines may prove to be useful to study both immune r esponse and replication of infectious agents in the absence of functional i nterferon receptors.