CpG-C ISS-ODN activation of blood-derived B cells from healthy and chronic immunodeficiency virus-infected macaques

Abstract

Cytosine-phosphate-guanine class C (CpG-C) immunostimulatory sequence oligodeoxynucleotides (ISS-ODNs) activate human B cells and dendritic cells (DCs), properties that suggest potential use as a novel adjuvant to enhance vaccine efficacy. After demonstrating that the CpG-C ISS-ODN C274 activates macaque DCs, we examined in vitro activation of macaque B cells by C274 as a prelude to evaluation of this molecule as an adjuvant in the testing of candidate human immunodeficiency virus vaccines in the rhesus macaque-simian immunodeficiency virus (SIV) model. C274 induced macaque CD20(+) B cells to proliferate more strongly than CD40 ligand or CpG-B ISS-ODN. C274 enhanced B cell survival; increased viability was most evident after 3-7 days of culture. Increased expression of CD40, CD80, and CD86 by B cells was apparent within 24 h of exposure to C274 and persisted for up to 1 week. C274-stimulated, B cell-enriched and peripheral blood mononuclear cell suspensions from naïve and immunodeficiency virus-infected monkeys secreted several cytokines [e.g., interleukin (IL)-3, IL-6, IL-12, interferon-alpha] and chemokines [e.g., monocyte chemoattractant protein-1/CC chemokine ligand 2 (CCL2), macrophage-inflammatory protein-1alpha/CCL3, IL-8/CXC chemokine ligand 8]. In comparison, exposure of macaque B cells to SIV had minimal impact on surface phenotype, despite inducing cytokine and chemokine production in cells from infected and uninfected animals. These observations emphasize the need to identify strategies to optimally boost immune function, as immunodeficiency viruses themselves only partially activate B cells and DCs. The ability of C274 to stimulate B cells and DCs in healthy and infected monkeys suggests its possible use as a broad-acting adjuvant to be applied in the rhesus macaque model for the development of preventative and therapeutic vaccines.

Local and Systemic Effects of Intranodally Injected CpG-C Immunostimulatory-Oligodeoxyribonucleotides in Macaques

“…Previous studies showed that CpG-B ISS-ODNs boosted vaccine efficacy in nonhuman primates (49 -55), but until recently there were no reports of CpG-C ISS-ODN usage in macaques (56). We found that the CpG-C ISS-ODN C274 activates macaque blood-derived DCs (17) and B cells (57) in vitro. This is supported by a recent report from Abel et al (58), documenting the responses of macaque blood and lymphoid PDCs to the different classes of CpG ISS-ODNs.…”

“…3. Just as for blood cells (17,57), in vitro exposure to C274 induced the most prominent up-regulation of CD80 and (less so) CD86 on Lin Ϫ HLA-DR ϩ CD123 ϩ PDCs and B cells in the LNC cultures (Fig. 3).…”

“…AT-2 SIV induced minimal changes in B cell phenotype (data not shown; as in blood; Ref. 57). CD80 and CD86 were highest in cells from ISS-ODNinjected LNs.…”

“…After 24 h (PBMCs and LNCs), 7 or 13 days (LNCs), cell-free supernatants were collected and stored at Ϫ20°C before ELISA and Luminex fluorescent bead assay analysis (Beadlyte Human 22-plex cytokine detection system recognizing macaque IL-1␤, -4, -5, -6, -8, -12 p40, GM-CSF, MCP-1/CCL2, MIP-1␣/CCL3, TNF-␣, RANTES/CCL5; Upstate Biotechnology). Although not listed as cross-reactive with macaque IL-3 by the manufacturers (after PBMC stimulation with PHA/PMA), IL-3 responses were detected upon C274 stimulation on the LNCs and PBMCs (57). Cell-free supernatants were analyzed for the presence of IL-12 p70 and the free p40 subunit and IFN-␣ by ELISA (BioSource International).…”

“…LNCs were cultured with ISS-ODNs, CD40L, or AT-2 SIV, stimuli that trigger macaque blood-derived MDC and PDC (17) as well as B cell (57) activation. This allows a better appreciation of the leukocyte function after in vivo ISS-ODN treatment and provides the first indication as to whether the cells remain responsive to repeated stimulation as would be needed to adjuvant a vaccine.…”