SummaryAnti-CD40 monoclonal antibodies (mAbs) that promote or inhibit receptor function hold promise as therapeutics for cancer and autoimmunity. Rules governing their diverse range of functions, however, are lacking. Here we determined characteristics of nine hCD40 mAbs engaging epitopes throughout the CD40 extracellular region expressed as varying isotypes. All mAb formats were strong agonists when hyper-crosslinked; however, only those binding the membrane-distal cysteine-rich domain 1 (CRD1) retained agonistic activity with physiological Fc gamma receptor crosslinking or as human immunoglobulin G2 isotype; agonistic activity decreased as epitopes drew closer to the membrane. In addition, all CRD2-4 binding mAbs blocked CD40 ligand interaction and were potent antagonists. Thus, the membrane distal CRD1 provides a region of choice for selecting CD40 agonists while CRD2-4 provides antagonistic epitopes.

This study addresses the relative importance of CD134 (OX40) and CD137 (4‐1BB) in the costimulation of CD4+ and CD8+ T cells under comparable conditions of antigenic stimulation. We demonstrate that CD134 is capable of directly costimulating CD8+ T cells. However, costimulation of CD8+ T cells by CD134 is less potent than that triggered by CD137. The higher costimulatory activity of CD137, when compared with CD134, correlates well with its faster expression kinetics and higher levels on CD8+ T cells. Furthermore, induction of CD137 expression on CD8+ T cells is highly sensitive to low levels of TCR stimulation, which is in contrast with CD134. Conversely, CD134 is more effective than CD137 in costimulating CD4+ T cells. This, however, could not be attributed to differential expression. We also demonstrate that the transient nature of CD134 and CD137 expression on activated CD4+ T cells is the resultof proteolytic shedding. Consistent with the greater ability of CD137 to costimulate CD8+ T cells, stimulation of CD137 in vivo is considerably more effective than CD134 in augmenting anti‐tumor immune responses. Therefore, agents that stimulate signaling via CD137 are likely to be more useful in clinical conditions where highly effective CD8+ CTL responses are required.

Rapid inactivation of Ebola virus (EBOV) is crucial for high-throughput testing of clinical samples in low-. In response to this outbreak, the international community has deployed an increasing number of Ebola diagnostic laboratories into the main West African countries affected (Guinea, Liberia, and Sierra Leone). Rapid diagnosis of EVD in humans is critical in the management of this disease in outbreak situations, as it allows prompt isolation and the chance to provide the best supportive care to patients, which helps reduce the overall infection rate and break the transmission chain.The preferred clinical sample for testing for Ebola virus (EBOV), an enveloped negative-sense single-strand RNA virus, is EDTA-blood, serum, or plasma with the primary diagnostic technology being real-time PCR (2). Other sample types, such as swabs or urine, may also be received by a laboratory. EBOV is designated in the United Kingdom by the Advisory Committee on Dangerous Pathogens (ACDP) as a hazard group 4 pathogen that must be handled under containment level (CL) 4 standards (biosafety level 4 [BSL4] in other countries). As such stringent laboratory infrastructure and containment procedures are required to handle viable EBOV material, only a few laboratories in Europe and elsewhere are suitably equipped (3). Within the timelines and budgets available, it has been impractical to create this laboratory infrastructure in West Africa, and therefore diagnostic laboratories have relied on methods that rapidly inactivate EBOV prior to routine processing and testing of samples by PCR.Laboratory methods of EBOV inactivation include gamma irradiation (4), nanoemulsion (5), photoinducible alkylating agents (6), and UV radiation (7), but these methods are primarily used for research purposes and may not be practicable in an outbreak situation that is likely to involve a high number of samples but reduced capability for handling and manipulation. In this context, any inactivation method must also be compatible with the EBOV PCR diagnostic approach.The CDC recommends Triton X-100 and heat treatment for 1 h for diagnostic samples containing hemorrhagic fever viruses (8), and this method has been adopted by many laboratories for handling of samples that may contain EBOV (9). Heating (alone or with acetic acid) for 1 h at 60°C has also been shown to reduce the titer of EBOV (10). Other guidelines can be nonspecific, specifying only the need for inactivation but not suggesting how (11) or suggesting generic use of denaturing/lysis buffers and/or heat (12). In the United Kingdom, the Advisory Committee on Dangerous Pathogens guidelines state that samples from confirmed cases may be processed in a containment level 2 laboratory using routine autoanalyzers if a containment level 4 laboratory is not available and provided specific procedures are followed (13). Within these guidelines, which encompass the application of multiple clinical tests, there is no specific requirement to inactivate EBOV (or other viral hemorrhagic fever agents) within a sa...

In this study we demonstrate that treatment with anti-CD40 mAb eradicates a range of mouse lymphomas (BCL1, A31, A20, and EL4), but only when used against i.v. tumor doses in excess of 107 cells. Only partial protection was seen against smaller tumor loads. We saw no evidence that anti-CD40 mAb changed the phenotype of the lymphomas or inhibited their growth in the initial period following treatment, but it did result in a rapid expansion of cytotoxic CD8+ cells that was able to clear the neoplastic disease and provide long-term protection against tumor rechallenge. The CTL responses were blocked by mAb against a range of coreceptors and cytokines, including CD8, B7-1, B7-2, LFA-1, and IFN-γ, but not CD4 or CTLA-4, indicating the presence of a conventional cellular Th1 response. Furthermore, we found evidence of cross-recognition between lymphomas (BCL1 and A20) as measured by cytotoxicity and IFN-γ responses in vitro and using tumor rechallenge experiments, suggesting common target Ags. Finally, although anti-CD40 was shown to stimulate NK cell killing, we could find no role for these cells in controlling tumor growth. These data underline the ability of anti-CD40 mAb to potentiate CTL responses and the potency of cellular immunity in eradicating large quantities of syngeneic tumor.