Melanoma immunotherapy by targeted IL-2 depends on CD4(+) T-cell help mediated by CD40/CD40L interaction

The induction of tumor-protective immunity against malignancies remains a major challenge in cancer immunotherapy. A novel, humanized anti-ganglioside-GD(2)-IL-2 immunocytokine (hu14.18-IL-2) induced CD8(+) T cells to eradicate established pulmonary metastases of B78-D14 murine melanoma, in a process that required help by CD4(+) T cells and was mediated by the CD40/CD40 ligand (CD40L) interaction. The anti-tumor effect was diminished in mice deficient in CD4(+) T-cells. Three lines of evidence show that CD4(+) T-cell help was mediated by CD40/CD40L interaction but not by endogenous IL-2 production. First, the hu14.18-IL-2-induced anti-tumor response is partially abrogated in C57BL/6J CD40L knockout (KO) mice in contrast to C57BL/6J IL-2 KO animals, in which the immunocytokine was completely effective. Second, partial abrogation of the anti-tumor effect is induced with anti-CD40L antibodies to the same extent as with CD4(+) T-cell depletion. Third, a complete anti-tumor response induced by hu14.18-IL-2 can be reconstituted in C57BL/6J CD40L KO mice by simultaneous stimulation with an anti-CD40 mAb. These results suggest that help provided by CD4(+) T cells via CD40/CD40L interactions in our tumor model is crucial for effective immunotherapy with an IL-2 immunocytokine.     

The effect of empiric antibiotic therapy on mortality in debilitated patients with dementia

The purpose of this investigation was to assess the effect of empirical antibiotic treatment on 30-day mortality among debilitated inpatients with dementia and Gram-negative bacteremia. A retrospective cohort study in the years 2005–2007 was undertaken. Data were collected through patient chart review. The association between individual variables and 30-day mortality was assessed through univariate analysis. Variables significantly associated with mortality (p < 0.05) were entered into a logistic regression analysis. Adjusted odds ratios (ORs) for mortality with 95% confidence intervals (CIs) are shown. Subgroup analysis of patients with and without decubitus ulcers was performed. In our cohort of 378 patients with dementia and Gram-negative bacteremia, the 30-day mortality was 39% overall and 61% in the subgroup of patients with decubitus ulcers. Inappropriate empirical therapy was associated with higher mortality, although this effect was not statistically significant (OR 1.41, 95% CI 0.86–2.29). Inappropriate empirical therapy did not affect mortality in the subgroup of patients with decubitus ulcers (OR 0.37, 95% CI 0.11–1.28). Other factors found to independently affect mortality included age, co-morbidities, source of infection, sepsis severity, and hospital-acquired infection. Appropriate empirical antibiotic therapy for patients with dementia and severe bacterial infection did not have a clear advantage, especially in the sickest group of patients with decubitus ulcers.     

Activation of human complement by human lymphoid cells sensitized with histocompatibility alloantisera

Cultured human lymphoid cells sensitized with human histocompatibility (HL-A) antibodies were able to activate the human complement system in vitro. Some HL-A alloantisera selectively activated the alternate complement pathway while other antisera activated only the classical pathway. A third group of alloantisera was equally able to initiate complement action by way of either pathway. The mechanism of complement activation did not correlate with the HL-A antigen present on the cells or the HL-A specificity of the alloantisera, indicating that the antigenic determinants or distribution on the cell surface play on direct role in selecting the pathway of activation. In this completely homologous system the alternate pathway was found to have the same cytolytic potential as the classical pathway. Thus, an altered or damaged membrane is not a prerequisite for the production of cytolytic damage by the alternate pathway. A complete understanding of the mechanism of interaction of membrane bound antigens and antibodies with the complement system may provide a versatile tool for the investigation of membrane antigen expression.     

DNA-based vaccines activate innate and adaptive antitumor immunity by engaging the NKG2D receptor

The interaction of NKG2D, a stimulatory receptor expressed on natural killer (NK) cells and activated CD8(+) T cells, and its ligands mediates stimulatory and costimulatory signals to these cells. Here, we demonstrate that DNA-based vaccines, encoding syngeneic or allogeneic NKG2D ligands together with tumor antigens such as survivin or carcinoembryonic antigen, markedly activate both innate and adaptive antitumor immunity. Such vaccines result in highly effective, NK- and CD8(+) T cell-mediated protection against either breast or colon carcinoma cells in prophylactic and therapeutic settings. Notably, this protection was irrespective of the NKG2D ligand expression level of the tumor cells. Hence, this strategy has the potential to lead to widely applicable and possibly clinically useful DNA-based cancer vaccines.     

Aglycosylated chimeric mouse/human IgG1 antibody retains some effector function

The N-linked carbohydrate attachment site of human IgG1 Ab has been eliminated by site-directed mutagenesis. Effector functions of aglycosylated Ab was then compared to its native counterpart. Aglycosylated Ab failed to exhibit any ADCC activity, but a significant level of CDC activity was retained by the aglycosylated Ab. These observations differ from those reported previously. Serum half-life and biodistribution of aglycosylated Ab in mice were comparable to the native Ab. Together, these results show that some, but not all, effector functions of a human IgG1 Ab are affected by aglycosylation.