Antibiotic-induced fever in orthopaedic patients-a diagnostic challenge.

INTRODUCTION: Antibiotic-induced fever is a probably underestimated complication, which may be misdiagnosed as new infection. In this study, characteristics, diagnostic approach, and outcome of antibiotic-induced fever in patients treated for musculoskeletal infections are described. METHODS: We retrospectively reviewed all patients with antibiotic-induced fever after surgery treated at our institution from 2014 to 2017. Antibiotic-induced fever was diagnosed, if the following criteria were fulfilled: (i) central (ear) body temperature > 38.0 °C; (ii) intravenous antibiotics for > three days; (iii) exclusion of infectious or other non-infectious causes of fever; and (iv) defervescence after discontinuation of antibiotics. RESULTS: We included 11 patients (median age 51 years) treated for infection after fracture fixation (n = 5), periprosthetic joint infections (n = 3), infection after spinal instrumentation (n = 1), and soft tissue infection (n = 2). The suspected antibiotics inducing fever were beta-lactam antibiotics (n = 9), vancomycin (n = 3), daptomycin (n = 2), clindamycin, and meropenem (n = 1 each). Additional clinical findings were reduced general condition, generalized exanthema, and rigors, whereas five patients were asymptomatic apart from a fever. Leukopenia was observed in nine patients and increase of C-reactive protein value in ten patients. Fever occurred after a median of 20 days of antibiotic treatment and resolved after a median of one day after discontinuation of the suspected antibiotic. CONCLUSIONS: Antibiotics should be considered as the possible cause of fever in orthopaedic patients receiving antimicrobial treament whenever clinical signs of new or persisting infection are lacking. Important hints suggestive for antibiotic-induced fever are good general condition despite high temperature and progressive leukopenia. Discontinuation or change to another substance leads to prompt defervescence, preventing unnecessary diagnostic procedures and antibiotic treatment.

Dendritic cell-based vaccination of patients with advanced pancreatic carcinoma: results of a pilot study.

BACKGROUND AND AIMS: Dendritic cell (DC)-based vaccination can induce antitumor T cell responses in vivo. This clinical pilot study examined feasibility and outcome of DC-based tumor vaccination for patients with advanced pancreatic adenocarcinoma. METHODS: Tumor lysate of patients with pancreatic carcinoma was generated by repeated freeze-thaw cycles of surgically obtained tissue specimens. Patients were eligible for DC vaccination after recurrence of pancreatic carcinoma or in a primarily palliative situation. DC were generated from peripheral blood mononuclear cells (PBMC), loaded with autologous tumor lysate, stimulated with TNF-α and PGE(2) and injected intradermally. All patients received concomitant chemotherapy with gemcitabine. Disease response was the primary endpoint. Individual immunological responses to DC vaccination were analyzed by T cell-based immunoassays using pre- and post-vaccination samples of non-adherent PBMC. RESULTS: Twelve patients received DC vaccination and concomitant chemotherapy. One patient developed a partial remission, and two patients remained in stable disease. Median survival was 10.5 months. No severe side effects were observed. Tumor-reactive T cells could be detected prior to vaccination. DC vaccination increased the frequency of tumor-reactive cells in all patients tested; however, the degree of this increase varied. To quantify the presence of tumor-reactive T cells, stimulatory indices (SI) were calculated as the ratio of proliferation-inducing capacity of lysate-loaded versus -unloaded DC. The patient with longest overall survival of 56 months had a high SI of 6.49, indicating that the presence of a pre-vaccination antitumor T cell response might be associated with prolonged survival. Five patients survived 1 year or more. CONCLUSION: DC-based vaccination can stimulate an antitumoral T cell response in patients with advanced or recurrent pancreatic carcinoma receiving concomitant gemcitabine treatment.

Combined use of toll-like receptor agonists and prostaglandin E(2) in the FastDC model: rapid generation of human monocyte-derived dendritic cells capable of migration and IL-12p70 production.

Phenotypical maturation, IL-12p70 production and migration upon chemokine receptor CCR7 ligation are currently proposed as requirements for the use of human monocyte-derived dendritic cells (DC) in antitumoral vaccination. We have previously described a short-term protocol for DC generation from monocytes including stimulation with TNF-alpha, IL-1beta and PGE(2) (FastDC). These "conventional" FastDC are mature, migrate in response to CCR7 ligation and effectively stimulate autologeous T cells in vitro, but are deficient in IL-12p70 production. Here, conventional FastDC were compared to FastDC activated with different TLR ligands. High levels of IL-12p70 were induced by combined activation of FastDC with TLR4 and TLR7/8 ligands. IL-12 secretion could be maximized by additional T cell-derived stimulation. However, TLR-stimulated FastDC failed to migrate upon CCR7 ligation, independent of additional activation with CD40 ligand and IFN-gamma. The presence of PGE(2) during TLR ligation fully restored migratory capacity of FastDC, but left IL-12p70 production and activation of tumor antigen-specific cytotoxic T cells unaffected, challenging previous findings obtained with standard 7-day monocyte-derived DC. The FastDC model thus not only represents an effective tool for antitumoral vaccination, but may also provide novel insights into human DC biology.

IFN-alpha promotes definitive maturation of dendritic cells generated by short-term culture of monocytes with GM-CSF and IL-4.

Dendritic cells (DC) generated in vitro have to be viable and phenotypically mature to be capable of inducing T cell-mediated immunity after in vivo administration. To facilitate optimization of DC-based vaccination protocols, we investigated whether the cytokine environment and the mode of activation affect maturation and survival of DC derived from monocytes by a short-term protocol. Monocytes cultured for 24 h with granulocyte macrophage-colony stimulating factor and interleukin-4 were stimulated with proinflammatory mediators for another 36 h to generate mature DC. Additional activation with CD40 ligand and interferon (IFN)-gamma increased viability of DC and promoted definitive maturation as defined by maintenance of a mature phenotype after withdrawal of cytokines. Addition of IFN-alpha to DC cultures prior to stimulation further enhanced definitive maturation: IFN-alpha-primed DC expressed high levels of costimulatory molecules and CC chemokine receptor 7 (CCR7) up to 5 days after cytokine withdrawal. Compared with unprimed DC, IFN-alpha-primed DC displayed equal capacity to migrate upon CCR7 ligation and to prime antigen-specific T helper cell as well as cytolytic T cell responses. In conclusion, we show that optimal maturation and survival of monocyte-derived DC require multiple activation signals. Furthermore, we identified a novel role for IFN-alpha in DC development: IFN-alpha priming of monocytes promotes definitive maturation of DC upon activation.

FastDC derived from human monocytes within 48 h effectively prime tumor antigen-specific cytotoxic T cells.

Previously, we have shown that dendritic cells (DCs) with full T-cell stimulatory capacity can be derived from human monocytes after 48 h of in vitro culture (FastDC). Compared to a standard 7-day protocol, this new strategy not only reduces the time span and the amount of recombinant cytokines required, but may also resemble DC development in vivo more closely. Using a melanoma antigen model, we show here that FastDC prime CTL responses against tumor antigens as effectively as standard monocyte-derived DCs (moDCs). FastDC and moDCs derived from monocytes of HLA-A2(+) donors were loaded with the melanoma-associated, HLA-A(*)0201-restricted peptide Melan-A and cocultured with autologous CD3(+) T cells. After two weekly restimulations with freshly prepared, peptide-loaded FastDC or moDCs, binding of CD8(+) T cells to fluorescently labeled MHC-I/Melan-A-peptide complexes and intracellular cytokine staining revealed that the two DC preparations had an equal capacity to prime Melan-A-specific, IFN-gamma producing CD8(+) T cells. CTLs derived from cocultures with FastDC lysed Melan-A-loaded T2 cells even more effectively than CTLs primed by moDCs. Comparative analysis also revealed that FastDC possess an equal capacity to migrate in response to the chemokine receptor CCR-7 ligand 6Ckine. Importantly, DCs can be generated with higher yield and purity using the FastDC-protocol. The reliability and efficacy of this new strategy for DC development from monocytes may facilitate clinical investigation of DC-based tumor immunotherapy.