CD30/CD30 ligand and CD40/CD40 ligand in malignant lymphoid disorders

CD30 and CD40 are members of the tumor necrosis factor (TNF) receptor family. These two receptors have pleiotropic biologic functions including induction of apoptosis and enhancing cell survival. This review will discuss the pattern of expression of these receptors in malignant lymphoid disorders and their prospective ligands. Understanding issues related to these two ligands and their receptors in lymphoid malignancies may help to improve the classification of these diseases and could open the doors for new treatment strategies.     

Follicular lymphoma intratumoral CD4+CD25+GITR+ regulatory T cells potently suppress CD3/CD28-costimulated autologous and allogeneic CD8+CD25- and CD4+CD25- T cells

Regulatory T cells (T(R)) play a critical role in the inhibition of self-reactive immune responses and as such have been implicated in the suppression of tumor-reactive effector T cells. In this study, we demonstrate that follicular lymphoma (FL)-infiltrating CD8+ and CD4+ T cells are hyporesponsive to CD3/CD28 costimulation. We further identify a population of FL-infiltrating CD4+CD25+GITR+ T(R) that are significantly overrepresented within FL nodes (FLN) compared with that seen in normal (nonmalignant, nonlymphoid hyperplastic) or reactive (nonmalignant, lymphoid hyperplastic) nodes. These T(R) actively suppress both the proliferation of autologous nodal CD8+CD25- and CD4+CD25- T cells, as well as cytokine production (IFN-gamma, TNF-alpha and IL-2), after CD3/CD28 costimulation. Removal of these cells in vitro by CD25+ magnetic bead depletion restores both the proliferation and cytokine production of the remaining T cells, demonstrating that FLN T cell hyporesponsiveness is reversible. In addition to suppressing autologous nodal T cells, these T(R) are also capable of suppressing the proliferation of allogeneic CD8+CD25- and CD4+CD25- T cells from normal lymph nodes as well as normal donor PBL, regardless of very robust stimulation of the target cells with plate-bound anti-CD3 and anti-CD28 Abs. The allogeneic suppression is not reciprocal, as equivalent numbers of CD25+FOXP3+ cells derived from either normal lymph nodes or PBL are not capable of suppressing allogeneic CD8+CD25- and CD4+CD25- T cells, suggesting that FLN T(R) are more suppressive than those derived from nonmalignant sources. Lastly, we demonstrate that inhibition of TGF-beta signaling partially restores FLN T cell proliferation suggesting a mechanistic role for TGF-beta in FLN T(R)-mediated suppression.     

CD154 (CD40 ligand)

CD40 ligand, a type II transmembrane protein recently renamed CD154, was originally considered restricted to activated T lymphocytes, functioning as a mediator of T cell-dependent B cell activation, proliferation, and differentiation. However, the spectrum of CD154 expression and function has broadened considerably during recent years, establishing new roles as a central mediator of immunity and inflammation for this member of the tumor necrosis factor (TNF) gene superfamily. The emerging picture indicates that ligation of the receptor CD40 via CD154, most potently in its trimeric form, functions in two ways. CD154 modulates physiologic processes, such as T cell-mediated effector functions and general immune responses required for appropriate host defense, but also triggers the expression of pro-inflammatory mediators, such as cytokines, adhesion molecules, and matrix degrading activities, all of which are associated with the pathogenesis of chronic inflammatory diseases, e.g., autoimmune disorders, arthritis, atherosclerosis, and cancer. Accordingly, CD40/CD154 interactions have advanced as a potential therapeutic target for these diseases, whereby two opposing strategies, interruption as well as enhancement of CD40 signaling, are explored for beneficial outcomes.     

CD30/CD30 ligand (CD153) interaction regulates CD4+ T cell-mediated graft-versus-host disease

CD30, a TNFR family member, is expressed on activated CD4(+) and CD8(+) T cells and B cells and is a marker of Hodgkin's lymphoma; its ligand, CD30L (CD153) is expressed by activated CD4(+) and CD8(+) T cells, B cells, and macrophages. Signaling via CD30 can lead to proliferation or cell death. CD30-deficient (-/-) mice have impaired thymic negative selection and increased autoreactivity. Although human alloreactive T cells preferentially reside within the CD30(+) T cell subset, implicating CD30 as a regulator of T cell immune responses, the role of CD30/CD153 in regulating graft-vs-host disease (GVHD) has not been reported. We used a neutralizing anti-CD153 mAb, CD30(-/-) donor mice, and generated CD153(-/-) recipient mice to analyze the effect of CD30/CD153 interaction on GVHD induction. Our data indicate that the CD30/CD153 pathway is a potent regulator of CD4(+), but not CD8(+), T cell-mediated GVHD. Although blocking CD30/CD153 interactions in vivo did not affect alloreactive CD4(+) T cell proliferation or apoptosis, a substantial reduction in donor CD4(+) T cell migration into the gastrointestinal tract was readily observed with lesser effects in other GVHD target organs. Blockade of the CD30/CD153 pathway represents a new approach for preventing CD4(+) T cell-mediated GVHD.     

CD134L engagement enhances human B cell Ig production: CD154/CD40, CD70/CD27, and CD134/CD134L interactions coordinately regulate T cell-dependent B cell responses

CD134 is a member of the TNFR family expressed on activated T cells, whose ligand, CD134L, is found preferentially on activated B cells. We have previously reported that the CD70/CD27 interaction may be more important in the induction of plasma cell differentiation after the expansion phase induced by the CD154/CD40 interaction has occurred. When CD134-transfected cells were added to PBMCs stimulated with pokeweed mitogen, IgG production was enhanced in a dose-dependent fashion. Addition of CD134-transfected cells to B cells stimulated with Staphylococcus aureus Cowan I strain/IL-2 resulted in little if any enhancement of B cell IgG production and proliferation. We found that while CD134-transfected cells induced no IgG production by themselves, it greatly enhanced IgG production in the presence of CD40 stimulation or T cell cytokines such as IL-4 and IL-10. The addition of CD134-transfected cells showed only a slight increase in the number of plasma cells compared with that in the culture without them, indicating that an increased Ig production rate per cell is responsible for the observed enhancing effect of CD134L engagement rather than increase in plasma cell generation. These results strongly suggest different and sequential roles of the TNF/TNFR family molecules in human T cell-dependent B cell responses through cell-cell contacts and the cytokine network.     

Mesenchymal stromal cells impair the differentiation of CD14(++) CD16(-) CD64(+) classical monocytes into CD14(++) CD16(+) CD64(++) activate monocytes

Background aimsMesenchymal stromal cells (MSC) possess immunomodulatory activity both in vitro and in vivo. However, little information is available regarding their function during the initiation of immunologic responses through their interactions with monocytes. While many studies have shown that MSC impair the differentiation of monocytes into dendritic cells and macrophages, there are few articles showing the interaction between MSC and monocytes and none of them has addressed the question of monocyte subset modulationMethodsTo understand better the mechanism behind the benefit of MSC infusion for graft-versus-host treatment through monocyte involvement, we performed mixed leucocyte reactions (MLR) in the presence and absence of MSC. After 3 and 7 days, cultures were analyzed by flow cytometry using different approachesResultsMSC induced changes in monocyte phenotype in an MLR. This alteration was accompanied by an increase in monocyte counting and CD14 expression. MSC induced monocyte alterations even without contact, although the parameters above were more pronounced with cell–cell contact. Moreover, the presence of MSC impaired major histocompatibility complex (MHC) I and II, CD11c and CCR5 expression and induced CD14 and CD64 expression on monocytes. These alterations were accompanied by a decrease in interleukin (IL)-1β and IL-6 production by these monocytes, but no change was observed taking into account the phagocytosis capacity of these monocytesConclusionsOur results suggest that MSC impair the differentiation of CD14⁺⁺ CD16^? CD64⁺ classical monocytes into CD14⁺⁺ CD16⁺ CD64⁺⁺ activated monocytes, having an even earlier role than the differentiation of monocytes into dendritic cells and macrophages.     

A ligand for CD5 is CD5

Recognition by scavenger receptor cysteine-rich domains on membrane proteins regulates innate and adaptive immune responses. Two receptors expressed primarily on T cells, CD5 and CD6, are linked genetically and are structurally similar, both containing three scavenger receptor cysteine-rich domains in their extracellular regions. A specific cell surface interaction for CD5 has been difficult to define at the molecular level because of the susceptibility of CD5 protein to denaturation. By using soluble CD5 purified at neutral pH to preserve biological activity, we show that CD5 mediates species-specific homophilic interactions. CD5 domain 1 only is involved in the interaction. CD5 mAbs that have functional effects in humans, rats, and mice block homophilic binding. Ag-specific responses by mouse T cells in vitro were increased when engagement of human CD5 domain 1 was inhibited by mutation or by IgG or Fab fragment from a CD5 mAb. This showed that homophilic binding results in productive engagement. Enhancement of polyclonal immune responses of rat lymph node cells by a Fab fragment from a CD5 mAb shown to block homophilic interactions provided evidence that the extracellular region of CD5 regulates inhibition in normal cells. These biochemical and in vitro functional assays provide evidence that the extracellular region of CD5 regulates immunity through species-specific homophilic interactions.     

Requirement of oxidation-dependent CD40 homodimers for CD154/CD40 bidirectional signaling

It is well established that the CD154/CD40 interaction is required for T cell-dependent B cell differentiation and maturation. However, the early molecular and structural mechanisms that orchestrate CD154 and CD40 signaling at the T cell/APC contact site are not well understood. We demonstrated that CD40 engagement induces the formation of disulfide-linked (dl) CD40 homodimers that predominantly associate with detergent-resistant membrane microdomains. Mutagenesis and biochemical analyses revealed that (a) the integrity of the detergent-resistant membranes is necessary for dl-CD40 homodimer formation, (b) the cytoplasmic Cys(238) of CD40 is the target for the de novo disulfide oxidation induced by receptor oligomerization, and (c) dl-CD40 homodimer formation is required for CD40-induced interleukin-8 secretion. Stimulation of CD154-positive T cells with staphylococcal enterotoxin E superantigen that mimics nominal antigen in initiating cognate T cell/APC interaction revealed that dl-CD40 homodimer formation is required for interleukin-2 production by T cells. These findings indicate that dl-CD40 homodimer formation has a physiological role in regulating bidirectional signaling.