Immunomodulatory dendritic cells require autologous serum to circumvent nonspecific immunosuppressive activity in vivo

Abstract

In immunotherapy, dendritic cells (DCs) can be used as powerful antigen-presenting cells to enhance or suppress antigenspecific immunity upon in vivo transfer in mice or humans. However, to generate sufficient numbers of DCs, most protocols include an ex vivo culture step, wherein the cells are exposed to heterologous serum and/or antigenic stimuli. In mouse models of virus infection and virus-induced autoimmunity, we tested how heterologous serum affects the immunomodulatory capacity of immature DCs generated in the presence of IL-10 by comparing fetal bovine serum (FBS)-or normal mouse serum (NMS)-supplemented DC cultures. We show that FBSexposed DCs induce a systemic immune deviation characterized by reduction of virus-specific T cells, delayed viral clearance, and enhanced systemic production of interleukin 4 (IL-4), IL-5, and IL-10 to FBS-derived antigens, including bovine serum albumin (BSA). By contrast, DCs generated in NMS-supplemented cultures modulated immunity and autoimmunity in an antigen-specific fashion. These cells did not induce systemic IL-4, IL-5, or IL-10 production and inhibited generation of virus-specific T cells or autoimmunity only if pulsed with a viral antigen. These data underscore the importance of using autologous serum-derived immature DCs in preclinical animal studies to accurately assess their immunomodulatory potential in future human therapeutic settings, where application of FBS is not feasible. IntroductionDendritic cells (DCs) are potent antigen-presenting cells important for induction of both tolerance and immunity, 1-3 and animal studies have sought to use these features to induce either antigen-specific immunity, antigen-specific tolerance, or antitumor immunity. 4,5 Methods have been developed to generate large numbers of DCs in vitro from spleen or bone marrow precursors in mice or from monocytes in humans. [6][7][8][9] Most of these protocols involve the use of growth factors such as granulocyte macrophage-colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), which can specifically promote DC generation. Other and less well-characterized factors are provided by, for example, heterologous fetal bovine serum (FBS), which has been used extensively.By nature, DCs sample their environment by antigen uptake, 10,11 and antigens are subsequently presented on major histocompatibility complex class I (MHC-I) and MHC-II molecules. Thus, in our opinion it is quite likely that DCs cultured in medium containing exogenous proteins will process and present not only an experimental antigen (eg, an antigenic peptide), but also antigens derived from heterologous proteins (eg, bovine serum albumin [BSA] from FBS). In addition, DCs rapidly respond to a variety of maturation and modulatory stimuli and it is not clear if and how a culture step in heterologous serum might affect subsequent DC function upon in vivo transfer.Nevertheless, DCs propagated or cultured in FBS-containing medium in vitro have been used in a number of different in vivo protocols, including attempts to immuni...

Differential Uptake and Processing of a Haemophilus influenzae P5-Derived Immunogen by Chinchilla Dendritic Cells

“…This observation was not without precedent, as the use of human-specific (and rat-specific) reagents for immunodetection is more successful than when one tries to use mousespecific reagents (27,29,63), which indirectly suggests that the chinchilla is closer to the rat and human than to mice in terms of similarity of immune molecules. Second, the serum source used to supplement the medium influenced the development of the culture, an observation similarly reported for murine DCs (24,61). Therefore, whereas it is not surprising that chinchillas possess DCs, our data are the first to describe their culture.…”

Antigen-dependent immunotherapy of non-obese diabetic mice with immature dendritic cells

“…DCs were generated largely as described [8,10,11]. In brief, bone marrow cells were harvested from the femur and tibiae from female prediabetic NOD mice (5-7 weeks of age) and washed in ice-cold Hanks's balanced salt solution (HBSS) following lysis of red blood cells.…”

“…by suppressing a concomitant Th1 response. Indeed, in these studies DCs presenting FBSderived antigens are capable of suppressing an otherwise robust anti-lymphocytic choriomeningitis virus (LCMV) virus response [8,9]. Thus, it is likely that DC therapy with FBS-exposed DCs may induce a dominant FBS-specific immune response rather than presenting islet-associated antigens in a tolerogenic and autoantigen-specific manner.…”

“…We have demonstrated recently that by generating DCs in the presence of normal mouse serum (NMS) rather than FBS, immature DCs capable of inducing antigen-specific immunological unresponsiveness can be generated from bone marrow cultures in vitro [8]. The mechanism was shown, at least partially, to involve abortive activation and induction of apoptosis in CD8 + T cells.…”

Autoantigen-Specific Immunotherapy

“…The von Herrath group explored this approach in a rat model (Haase et al, 2005). They utilized the rat insulin promoter (RIP)-LCMV model of T1D in which disease is induced upon LCMV infection.…”