Chronic allograft vasculopathy (CAV) in murine heart allografts can be elicited by adoptive transfer of donor specific antibody (DSA) to class I MHC antigens and is independent of complement. Here we address the mechanism by which DSA causes CAV. B6.RAG1−/− or B6.RAG1−/−C3−/− (H-2b) mice received B10.BR (H-2k) heart allografts and repeated doses of IgG2a, IgG1 or F(ab’)2 fragments of IgG2a DSA (anti-H-2k). Intact DSA regularly elicited markedly stenotic CAV in recipients over 28 days. In contrast, depletion of NK cells with anti-NK1.1 reduced significantly DSA-induced CAV, as judged morphometrically. Recipients genetically deficient in mature NK cells (γ-chain knock out) also showed decreased severity of DSA-induced CAV. Direct NK reactivity to the graft was not necessary. F(ab’)2 DSA fragments, even at doses twofold higher than intact DSA, were inactive. Graft microvascular endothelial cells responded to DSA in vivo by increased expression of phospho-extracellular signal-regulated kinase (pERK), a response not elicited by F(ab’)2 DSA. We conclude that antibody mediates CAV through NK cells, by an Fc dependent manner. This new pathway adds to the possible mechanisms of chronic rejection and may relate to the recently described C4d-negative chronic antibody-mediated rejection in humans.

The rising prevalence of HIV among pregnant women in rural India is of great concern. Prenatal voluntary counseling and HIV testing (VCT) is critical to prevent mother-to-child transmission of HIV (PMTCT). We surveyed 202 pregnant women attending a rural antenatal clinic in Southern India to investigate HIV-related knowledge, attitudes toward infant feeding practices, and perceived benefits and risks of HIV testing. Of the total of 202 women surveyed, 189 women (94%) had heard of HIV/AIDS and 60% of them had relatively good knowledge regarding risk factors for HIV transmission. However, 48% did not know that there are "means to prevent mother-to-child HIV transmission." If women were not to breastfeed her baby, negative attitudes expected from the partner would include 84% thinking that that the mother is harming the baby, 78% thinking she is not a good mother, 74% thinking she has HIV, and 66% thinking she has been unfaithful. Ninety-seven percent of women did not perceive themselves at risk for HIV and only 57% had been tested for HIV. Although, 85% of women expressed their willingness to be tested, most were concerned about confidentiality and disclosing HIV serostatus because of fear of negative reactions from their husbands, parents, and community. Many social and cultural barriers confront pregnant women when they decide to opt for HIV testing. If VCT and PMTCT interventions are to be successful, urgent attention must be focused on education, development of innovative culturally appropriate interventions that empower women to make decisions about HIV testing, involvement of men, and addressing stigma and discriminatory attitudes toward people living with HIV/AIDS.

The relative contribution of central and peripheral mechanisms to the generation and maintenance of allograft tolerance is of considerable interest. Here, we present new evidence that regulatory T cells (Foxp3+) maintain skin and heart allograft tolerance in mixed hematopoietic chimeric mice. Transient depletion of both donor‐ and recipient‐derived Foxp3+ cells was necessary and sufficient to induce decisive rejection of long‐accepted skin and heart allografts. In contrast, stable hematopoietic chimerism remained, and there was no detectable induction of donor‐specific reactivity to hematopoietic cells. Foxp3+ cell depletion did not result in the rejection of skin grafts of only MHC‐disparate donors (B6.C‐H2d/bByJ), indicating that MHC antigens were not the target in the graft. We conclude that two different mechanisms of tolerance are present in mixed chimeras. Hematopoietic chimerism, resistant to Foxp3+ depletion, is probably due to deletional tolerance to MHC antigens, as supported by previous studies. In contrast, regulatory tolerance mechanisms involving Foxp3+ cells are required to control reactivity against non‐MHC antigens not present on hematopoietic lineages.

Background: Chronic allograft vasculopathy (CAV) is a major mechanism of graft failure of transplanted organs in humans. Morphometric analysis of coronary arteries enables the quantitation of CAV in mouse models of heart transplantation. However, conventional histological procedures using single 2-dimensional sections limit the accuracy of CAV quantification. The aim of this study is to improve the accuracy of CAV quantification by reconstructing the murine coronary system in 3-dimensions (3D) and using virtual reconstruction and volumetric analysis to precisely assess neointimal thickness. Methods: Mouse tissue samples, native heart and transplanted hearts with chronic allograft vasculopathy, were collected and analyzed. Paraffin embedded samples were serially sectioned, stained and digitized using whole slide digital imaging techniques under normal and ultraviolet lighting. Sophisticated software tools were used to generate and manipulate 3D reconstructions of the major coronary arteries and branches. Results: The 3D reconstruction provides not only accurate measurements but also exact volumetric data of vascular lesions. This virtual coronary arteriography demonstrates that the vasculopathy lesions in this model are localized to the proximal coronary segments. In addition, virtual rotation and volumetric analysis enabled more precise measurements of CAV than single, randomly oriented histologic sections, and offer an improved readout for this important experimental model. Conclusions: We believe 3D reconstruction of 2D histological slides will provide new insights into pathological mechanisms in which structural abnormalities play a role in the development of a disease. The techniques we describe are applicable to the analysis of arteries, veins, bronchioles and similar sized structures in a variety of tissue types and disease model systems. Virtual slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/ 3772457541477230.