Anti-CD86 Antibody [GL-1] (A85872)

Background and purpose: Enhancing hematoma clearance through phagocytosis may reduce brain injury after intracerebral hemorrhage. In the current study, we investigated the role of cluster of differentiation 47 (CD47) in regulating erythrophagocytosis and brain injury after intracerebral hemorrhage in nude mice.

Methods: This study was in 2 parts. First, male adult nude mice had an intracaudate injection of 30 µL saline, blood from male adult wild-type (WT) mice, or blood from CD47 knockout mice. Second, mice had an intracaudate injection of 30 µL CD47 knockout blood with clodronate or control liposomes. Clodronate liposomes were also tested in saline-injected mice. All mice then had magnetic resonance imaging to measure hematoma size and brain swelling. Brains were used for immunohistochemistry and Western blot.

Results: Erythrophagocytosis occurred in and around the hematoma. Injection of CD47 knockout blood resulted in quicker clot resolution, less brain swelling, and less neurological deficits compared with wild-type blood. Higher brain heme oxygenase-1 levels and more microglial activation (mostly M2 polarized microglia) at day 3 were found after CD47 knockout blood injection. Co-injection of clodronate liposomes, to deplete phagocytes, caused more severe brain swelling and less clot resolution.

Conclusions: These results indicated that CD47 has a key role in hematoma clearance after intracerebral hemorrhage.

The nature of the T-cell response to antigen is governed by the activation state of the antigen-presenting dendritic cell (DC). Immature or resting DCs have been shown to induce T-cell responses that may protect against the development of autoimmune disease. Effectively harnessing this "tolerogenic" effect of resting DCs requires that it be disease-specific and that activation of DCs by manipulation ex vivo is avoided. We reasoned that this could be achieved by transferring in vivo partially differentiated myeloid progenitor cells encoding a disease-specific autoantigen. With the aim of preventing autoimmune diabetes, we transferred myeloid progenitor cells encoding proinsulin into NOD mice. Bone marrow (BM) was cultured in granulocyte macrophage colony-stimulating factor (GM-CSF) and transforming growth factor-beta1, a cytokine combination that expands myeloid cells but inhibits terminal DC differentiation, to yield Gr-1(+)/CD11b(+)/CD11c(-) myeloid progenitor cells and a minor population of CD11c(+)/CD11b(+)/CD86(lo) immature DCs. After transfer, Gr-1(+) myeloid cells acquired the characteristics of resting DCs (CD11c(+)/MHC classII(int)/CD86(lo)/CD40(lo)). Gr-1(+) myeloid cells generated from transgenic NOD mice that expressed proinsulin controlled by a major histocompatibility complex (MHC) class II promoter, but not from wild-type NOD mice, transferred into 4-week-old female NOD mice significantly suppressed diabetes development. The transfer of DC progenitors encoding a disease-specific autoantigen is, therefore, an effective immunotherapeutic strategy that could be applied to humans.

B cells leave the bone marrow as transitional B cells. Transitional B cells represent a target of negative selection and peripheral tolerance, both of which are abrogated in vitro by mediators of T cell help. In vitro, transitional and mature B cells differ in their responses to B cell receptor ligation. Whereas mature B cells up-regulate the T cell costimulatory molecule CD86 (B7.2) and are activated, transitional B cells do not and undergo apoptosis. The ability of transitional B cells to process and present Ag to CD4 T cells and to elicit protective signals in the absence of CD86 up-regulation was investigated. We report that transitional B cells can process and present Ag as peptide:MHC class II complexes. However, their ability to activate T cells and elicit help signals from CD4-expressing Th cells was compromised compared with mature B cells, unless exogenous T cell costimulation was provided. A stringent requirement for CD28 costimulation was not evident in interactions between transitional B cells and preactivated CD4-expressing T cells, indicating that T cells involved in vivo in an ongoing immune response might rescue Ag-specific transitional B cells from negative selection. These data suggest that during an immune response, immature B cells may be able to sustain the responses of preactivated CD4(+) T cells, while being unable to initiate activation of naive T cells. Furthermore, the ability of preactivated, but not naive T cells to provide survival signals to B cell receptor-engaged transitional immature B cells argues that these B cells may be directed toward activation rather than negative selection when encountering Ag in the context of a pre-existing immune response.

Murine dendritic cells (DCs) can be classified into at least 2 subsets, "myeloid-related" (CD11b(bright), CD8alpha(-)) and "lymphoid-related" (CD11b(dull), CD8alpha(+)), but the absolute relationship between the 2 remains unclear. Methods of generating DCs from bone marrow (BM) precursors in vitro typically employ granulocyte-macrophage colony-stimulating factor (GM-CSF) as the principal growth factor, and the resultant DCs exhibit a myeloidlike phenotype. Here we describe a flt3-ligand (FL)-dependent BM culture system that generated DCs with more diverse phenotypic characteristics. Murine BM cells cultured at high density in recombinant human FL for 9 days developed into small lymphoid-sized cells, most of which expressed CD11c, CD86, and major histocompatibility complex (MHC) class II. The CD11c(+) population could be divided into 2 populations on the basis of the level of expression of CD11b, which may represent the putative myeloid- and lymphoid-related subsets. The FL in vitro-derived DCs, when treated with interferon-alpha or lipopolysaccharide during the final 24 hours of culture, expressed an activated phenotype that included up-regulation of MHC class II, CD1d, CD8alpha, CD80, CD86, and CD40. The FL-derived DCs also exhibited potent antigen-processing and antigen-presenting capacity. Neutralizing anti-interleukin-6 (IL-6) antibody, but not anti-GM-CSF, significantly reduced the number of DCs generated in vitro with FL, suggesting that IL-6 has a role in the development of DCs from BM precursors. Stem cell factor, which exhibits some of the same bioactivities as FL, was unable to replace FL to promote DC development in vitro. This culture system will facilitate detailed analysis of murine DC development.