Clinical evidence suggests that cellular immunity is involved in controlling human immunodeficiency virus-1 (HIV-1) replication. An animal model of acquired immune deficiency syndrome (AIDS), the simian immunodeficiency virus (SIV)-infected rhesus monkey, was used to show that virus replication is not controlled in monkeys depleted of CD8+ lymphocytes during primary SIV infection. Eliminating CD8+ lymphocytes from monkeys during chronic SIV infection resulted in a rapid and marked increase in viremia that was again suppressed coincident with the reappearance of SIV-specific CD8+ T cells. These results confirm the importance of cell-mediated immunity in controlling HIV-1 infection and support the exploration of vaccination approaches for preventing infection that will elicit these immune responses.

Early and high-level production of IL-12 is crucial for effective immune responses against pathogens. Up until now, the cells providing this initial IL-12 have remained elusive. Here we show that a subset of human blood dendritic cells (DC) is the principal and primary source of IL-12p70 when blood leukocytes are stimulated with the TLR4-ligand LPS or with CD40-ligand. These so-called slanDC are characterized by the 6-sulfo LacNAc modification of PSGL-1, which is identified by the mAb M-DC8. The IL-12 response of slanDC requires a few hours of in vitro maturation, which is completely blocked in the presence of erythrocytes. This inhibition of maturation depends on the expression of CD47 on erythrocytes and of its ligand SIRPalpha on DC. While strictly controlled in the blood by erythrocytes, the high IL-12- and TNF-alpha-producing capacity of slanDC in tissues may be critical in fighting off pathogens; if uncontrolled, it may lead to adverse inflammatory reactions.

No abstract

The monoclonal antibody M-DC8 defines a major subset of human blood dendritic cells (DCs). Here we identify the M-DC8 structure as 6-sulfo LacNAc, a novel carbohydrate modification of the P selectin glycoprotein ligand 1 (PSGL-1). In contrast to previously described blood DCs, M-DC8+ DCs lack the cutaneous lymphocyte antigen (CLA) on PSGL-1 and fail to bind P and E selectin. Yet they express anaphylatoxin receptors (C5aR and C3aR) and the Fcgamma receptor III (CD16), which recruit cells to inflammatory sites. While sharing with DC1 the expression of myeloid markers and a potent capacity to prime T cells in vitro, M-DC8+ DCs produce far more TNF-alpha in response to the bacterial endotoxin lipopolysaccharide (LPS). Thus, 6-sulfo LacNAc-expressing DCs appear as a novel proinflammatory DC subset.

The receptor for advanced glycation endproducts (RAGE) is expressed under pathological conditions in many tissues and has been assigned many functions. We demonstrate, in normal human lung tissue, the preferential and highly abundant expression of RAGE by quantitative polymerase chain reaction. In addition, RAGE expression, as a specific differentiation marker of alveolar epithelial type I cells (AT I cells), and its localization to the basolateral plasma membrane have been confirmed by means of newly raised monoclonal antibodies. The physiological function of RAGE on AT I cells has previously remained elusive. By using HEK293 cells transfected with cDNA encoding for full-length RAGE, we show that RAGE enhances the adherence of epithelial cells to collagen-coated surfaces and has a striking capacity for inducing cell spreading. The preferential binding of RAGE to collagen has been confirmed by assaying the binding of soluble RAGE to various substrates. RAGE might thus assist AT I cells to acquire a spreading morphology, thereby ensuring effective gas exchange and alveolar stability.

Nonhuman primates provide valuable animal models for human diseases. However , studies assessing the role of cell-mediated immune responses have been difficult to perform in nonhuman primates. We have shown that CD8؉ lymphocyte-mediated immunity in rhesus monkeys can be selectively eliminated using the mouse-human chimeric anti-CD8 monoclonal antibody cM-T807. In vitro, this antibody completely blocked antigen-specific expansion of cytotoxic T cells and decreased major histocompatibility complex class I-restricted , antigen-specific lysis of target cells but did not mediate complement-dependent cell lysis. In vivo administration of cM-T807 in rhesus monkeys resulted in near total depletion of CD8؉ T cells from the blood and lymph nodes for up to 6 weeks. This depletion was not solely complementdependent and persisted longer in adults than in ju- Defining the role of the cellular and humoral components of the immune response to pathogens has furthered our understanding of the pathophysiology of various infectious diseases. Knowledge of these immune responses has also been valuable in designing immunization and other prophylactic strategies to prevent infection by these organisms. Animal models that permit passive administration of immunoglobulins or adoptive transfer of lymphocytes to naive hosts have been crucial for demonstrating the contribution of specific components of the immune response in controlling certain infections.Numerous experimental approaches have been used to study the role of CD8ϩ cell-mediated immunity in the control of infections. Studies demonstrating the importance of cellular immunity in various viral infections have been performed by adoptive transfer of lymphocytes in syngeneic mice. 1,2 Genetic knockout mice in which the CD8 or ␤ 2 microglobulin genes have been disrupted have been useful for defining the immunopathogenic role of cytotoxic T lymphocytes (CTL) in specific infectious agents. 3,4 Finally, rodents depleted of CD8ϩ lymphocytes by administration of CD8-specific monoclonal antibodies have been useful in determining the role of CTL in controlling pathogens.

Prognosis for patients suffering from malignant glioma has not substantially improved. Specific immunotherapy as a novel treatment concept critically depends on target antigens, which are highly overexpressed in the majority of gliomas, but the number of such antigens is still very limited. SOX2 was identified by screening an expression database for transcripts that are overexpressed in malignant glioma, but display minimal expression in normal tissues. Expression of SOX2 mRNA was further investigated in tumour and normal tissues by real-time PCR. Compared to cDNA from pooled normal brain, SOX2 was overexpressed in almost all (9 out of 10) malignant glioma samples, whereas expression in other, non-malignant tissues was almost negligible. SOX2 protein expression in glioma cell lines and tumour tissues was verified by Western blot and immunofluorescence. Immunohistochemistry demonstrated SOX2 protein expression in all malignant glioma tissues investigated ranging from 6 to 66% stained tumour cells. Human leucocyte antigen-A*0201-restricted SOX2-derived peptides were tested for the activation of glioma-reactive CD8 þ cytotoxic T lymphocytes (CTLs). Specific CTLs were raised against the peptide TLMKKDKYTL and were capable of lysing glioma cells. The abundant and glioma-restricted overexpression of SOX2 and the generation of SOX2-specific and tumour-reactive CTLs may recommend this antigen as target for T-cell-based immunotherapy of glioma.

Originating from a common progenitor cell, dendritic cells (DC) appear to develop along early branched pathways into various yet ill-defined subpopulations residing at various sites throughout the body where they capture and present antigen in the most professional fashion. Here we give evidence for a unique subpopulation of human DC circulating in blood that account for 0.5-1% of blood leukocytes only, their most specific characteristic being the expression of a cell surface protein recognized by a novel monoclonal antibody (M-DC8) which enables their isolation by a one-step immunomagnetic procedure. The isolated cells (> 97% pure) present morphologically as typical dendritic cells. They express the Fc(gamma)RIII (CD16), so far not found on DC, and avidly phagocytose latex beads as well as opsonized erythrocytes. These cells not only present antigens efficiently to naive T cells but also induce purified CD8+ T cells to become alloantigen-specific cytotoxic cells. Furthermore, when loaded with a tyrosinase-derived peptide they stimulate T cells from normal donors and melanoma patients to exhibit MHC-restricted specific cytotoxicity against melanoma cells.