Normal human immune peritoneal cells: phenotypic characteristics

Normal human peritoneal cells (PC) collected from patients with calculous cholecystitis without clinically detectable inflammatory changes were characterized morphologically, histochemically and phenotypically by means of monoclonal antibodies. The PC consisted of 45% of monocytes/macrophages (M718 + cells). Thirty-five per cent of PC were esterase-positive and 23% acid phosphatase positive. Forty-five per cent of PC adhered to glass surface. In the lymphocyte population, 2% of CD22 B lymphocytes (M738 +) and 42% CD2 T lymphocytes (M720+) were found. CD4/CD8 ratio was 0.4. There were 8% of Leu7 + cells. The PC did not reveal interleukin 2 (OKT26a +) and transferrin receptors (OKT9 +) on their surface. No blast cells were detected in the PC suspension. Approximately 49% of the PC expressed Ia antigens (OKIa1 +). Two per cent of S100 positive dendritic cells (Z311 +) were found. Peritoneal fluid contained 9% of granulocytes, mostly neutrophils. Two per cent of PC were free mesothelial cells (M717 +). We conclude that human peritoneal cavity contains a cell population significantly differing from that which is present in peripheral blood, which strongly suggests a non-random cell accumulation in the peritoneum. Lack of any activated cells indicates that under normal conditions the peritoneum lavage fluid contains a steady-state population. We conclude that the normal peritoneal fluid cells represent a heterogeneous population capable of reacting to various antigens entering the cavity from the gut.     

Mucosal immunoglobulins and B cells of teleost fish

As physical barriers that separate teleost fish from the external environment, mucosae are also active immunological sites that protect them against exposure to microbes and stressors. In mammals, the sites where antigens are sampled from mucosal surfaces and where stimulation of naïve T and B lymphocytes occurs are known as inductive sites and are constituted by mucosa-associated lymphoid tissue (MALT). According to anatomical location, the MALT in teleost fish is subdivided into gut-associated lymphoid tissue (GALT), skin-associated lymphoid tissue (SALT), and gill-associated lymphoid tissue (GIALT). All MALT contain a variety of leukocytes, including, but not limited to, T cells, B cells, plasma cells, macrophages and granulocytes. Secretory immunoglobulins are produced mainly by plasmablasts and plasma cells, and play key roles in the maintenance of mucosal homeostasis. Until recently, teleost fish B cells were thought to express only two classes of immunoglobulins, IgM and IgD, in which IgM was thought to be the only one responding to pathogens both in systemic and mucosal compartments. However, a third teleost immunoglobulin class, IgT/IgZ, was discovered in 2005, and it has recently been shown to behave as the prevalent immunoglobulin in gut mucosal immune responses. The purpose of this review is to summarise the current knowledge of mucosal immunoglobulins and B cells of fish MALT. Moreover, we attempt to integrate the existing knowledge on both basic and applied research findings on fish mucosal immune responses, with the goal to provide new directions that may facilitate the development of novel vaccination strategies that stimulate not only systemic, but also mucosal immunity.     

Mucosal immunoglobulins and B cells of teleost fish

As physical barriers that separate teleost fish from the external environment, mucosae are also active immunological sites that protect them against exposure to microbes and stressors. In mammals, the sites where antigens are sampled from mucosal surfaces and where stimulation of naïve T and B lymphocytes occurs are known as inductive sites and are constituted by mucosa-associated lymphoid tissue (MALT). According to anatomical location, the MALT in teleost fish is subdivided into gut-associated lymphoid tissue (GALT), skin-associated lymphoid tissue (SALT), and gill-associated lymphoid tissue (GIALT). All MALT contain a variety of leukocytes, including, but not limited to, T cells, B cells, plasma cells, macrophages and granulocytes. Secretory immunoglobulins are produced mainly by plasmablasts and plasma cells, and play key roles in the maintenance of mucosal homeostasis. Until recently, teleost fish B cells were thought to express only two classes of immunoglobulins, IgM and IgD, in which IgM was thought to be the only one responding to pathogens both in systemic and mucosal compartments. However, a third teleost immunoglobulin class, IgT/IgZ, was discovered in 2005, and it has recently been shown to behave as the prevalent immunoglobulin in gut mucosal immune responses. The purpose of this review is to summarise the current knowledge of mucosal immunoglobulins and B cells of fish MALT. Moreover, we attempt to integrate the existing knowledge on both basic and applied research findings on fish mucosal immune responses, with the goal to provide new directions that may facilitate the development of novel vaccination strategies that stimulate not only systemic, but also mucosal immunity.     

New phenotypic, functional and electrophysiological characteristics of KG-1 cells

Myeloid dendritic cells (DC) are representatives of a rare and phenotypically diverse population of professional antigen presenting cells possessing high functional heterogeneity and flexibility. Here we studied the phenotypic, functional and electrophysiological characteristics of KG-1 cells, an erythroleukemia model cell line, which shares morphological and physiological similarities with immature and mature myeloid DC. We compared the expression of internalizing receptors and other cell surface molecules, antigen uptake and migration of unstimulated and activated KG-1 cells with the characteristics of immature and mature DC. Unstimulated KG-1 cells were less potent in capturing extracellular materials than immature DC. In contrast to monocyte-derived DC KG-1 cells stimulated by PMA and ionomycin ceased to migrate along the MIP-3beta chemokine gradient despite their high expression of CCR7 chemokine receptor and MDR, a transporter implicated in DC migration. Moreover, we determined the ion channel repertoire of KG-1 cells before and after treatment with PMA and ionomycin by using the patch-clamp technique. We found that both unstimulated and activated KG-1 cells expressed time- and voltage-independent, ChTx sensitive intracellular Ca(2+)-gated potassium conductance suggesting the presence of K(Ca) channels in their membranes. Based on our results we propose that KG-1 cells resemble myeloid DC but also possess unique phenotypic, functional and electrophysiological characteristics.     

Porcine dendritic cells generated in vitro: morphological, phenotypic and functional properties.

Despite the central role that dendritic cells (DC) play in immune regulation and antigen presentation, little is known about porcine DC. In this study, two sources of DC were employed. Bone marrow haematopoietic cell-derived DC (BM-DC) were generated using granulocyte-macrophage colony-stimulating factor (GM-CSF) in the presence or absence of tumour necrosis factor-alpha (TNF-alpha). Monocyte-derived DC (Momicron-DC) were generated with GM-CSF and interleukin-4 (IL-4). In both systems, non-adherent cells developed with dendritic morphology, expressing high levels of major histocompatibility complex (MHC) class II. The presence of TNF-alpha increased the BM-DC yield, and enhanced T-cell stimulatory capacity. Both BM-DC and Momicron-DC expressed the pan-myeloid marker SWC3, as well as CD1 and CD80/86, but were also CD14+ and CD16+. The CD16 molecule was functional, acting as a low-affinity Fc receptor. In contrast, the CD14 on DC appeared to differ functionally from monocyte CD14: attempts to block CD14, in terms of lipopolysaccharide (LPS)-induced procoagulant activity (PCA), failed. The use of TNF-alpha or LPS for DC maturation induced up-regulation of MHC class II and/or CD80/86, but also CD14. Allogeneic mixed leucocyte reactions and staphylococcal enterotoxin B antigen presentation assays demonstrated that these DC possessed potent T-cell stimulatory capacity. No T helper cell polarization was noted. Both the BM-DC and the Momicron-DC induced a strong interferon-gamma and IL-4 response. Taken together, porcine DC generated in vitro possess certain characteristics relating them to DC from other species including humans, but the continued presence of CD14 and CD16 on mature and immature porcine DC was a notable difference.     

Unique phenotypic profile of monocytoid B cells: differences in comparison with the phenotypic profile observed in marginal zone B cells and so-called monocytoid B cell lymphoma

Monocytoid B cells (MBCs) are a subset of B cells that may be recognized in several reactive and tumoral lymph node conditions, including toxoplasmic lymphadenitis, infectious mononucleosis, and Hodgkin's lymphoma. Although this is a commonly observed cell population, which has even given its name to a type of lymphoma, MBC lymphoma, scarcely any information is available about the function and characteristics of this cell type. A relationship with marginal zone (MZ) B lymphocytes has been claimed for MBCs, but this has not yet been fully proven. Indeed, specific markers for MBCs are still lacking, which has made it difficult to analyze their relationship with other B cell subpopulations and confirm the existence of tumors deriving from this B cell subset. We used a panel of cell cycle markers to explore the characteristics of MBCs and their relationship with MZ B cells, nodal MZ lymphoma, and splenic MZ lymphoma. We therefore compared the phenotypic profile of MBCs in different conditions with normal MZ B cells within the spleen and mesenteric lymph nodes, with a group of seven cases of nodal MZ/MBC lymphoma and another group of five cases of splenic MZ lymphoma. MBCs were mainly in the G(0) to G(1) phases, as deduced from the presence of a proportion of between 10 and 35% Ki67-positive cells, whereas very low expression was observed with cyclin A and cyclin B staining. Nests of MBCs were clearly labeled by the expression of p21(WAF1), a cyclin-dependent kinase inhibitor (CKI), rarely detectable in benign lymphocytes, and by cyclin E. Basically all MBCs were bcl-2-negative, and high cyclin D2 and cyclin D3 were also detected in these cells, at proportions and intensities above expected levels, when the percentage of proliferating cells was taken into account. p27(KIP1) expression was characterized by homogeneous reactivity, higher than that observed in other B cell populations with a relatively high-growth fraction. Immunoglobulin staining showed undetectable light and heavy chains. However, splenic MZ cells, nodal MZ lymphoma, and splenic MZ lymphoma showed a distinct expression of IgM and bcl-2, with high p27 (KIP1) nuclear expression and undetectable or low levels of cyclin A, B, E, or D, or p21(WAF1) expression. The data from this study show an unexpected immunophenotype in MBCs, different from the one observed in splenic and lymph node MZ B cells. This suggests that either MBCs are a unique B cell population from a distinct cell lineage, or if related to MZ cells, they would represent a definite differentiation stage characterized by a distinctive immunophenotype. They also show so-called MZ/MBC lymphoma to be more closely related to lymph node and splenic MZ B cells, as they do not share the most distinctive features of MBCs.     

Ciliated gastric cells: a study of their phenotypic characteristics

Ciliated cells are found in the basal segments of antral glands whose superficial segments have undergone intestinal metaplasia. The affected cells resemble antral rather than metaplastic intestinal cells. This impression is supported by the immunohistochemical demonstration of pepsinogen group II production and ultrastructural demonstration of pepsinogen granules in the involved segments. Abnormal ciliogenesis in these cells resembles a possibly reversible change in bronchial epithelium that accompanies stasis of secretion and chronic inflammation. Affected antral cells show an evidence of decreased mitotic activity, but the multiplicity of cilia in each affected cell suggests that they stem from the continuing propagation of centriole-basal bodies.     

Dendritic cells, B cells and the regulation of antibody synthesis

Summary: Dendritic cells (DC) are usually thought of as antigen-presenting cells for T cells. However, recent studies from our laboratory and those of others have shown that they have important roles in B-cell activation and regulation of antibody synthesis. Rat DC make short term interactions with resting B cells and these interactions can be stimulated by cross-linking molecules on either cell surface. These DC can retain antigen in native form for at least 36 h in vivo and in vitro and can subsequently release it for recognition by B cells. In vivo antibody responses induced by antigen-pulsed DC are skewed towards IgG. In vitro, naive B cells incubated with antigen-pulsed DC subsequently secrete IgM and IgG when cultured with an antigen-specific CD4⁺ T-cell line, whereas if B cells are incubated with antigen without DC, only IgM is produced. These observations show that DC play an important role in the initiation of and regulation of antibody synthesis.     

Functional and phenotypic characteristics of bovine natural cytotoxic cells

Bovine natural cytotoxic (NC) cell activity of peripheral blood leukocytes (PBL) was studied in a chromium release assay, using xenogeneic tumor cells (YAC-1, P815) and herpes virus-infected bovine fibroblasts. The activity pattern resembled that of murine natural killer cells, in that YAC-1 cells were readily lysed, whereas P815 cells were resistant. However, 10-16 h of incubation were usually required to give appreciable cell lysis. Low, but consistent NC-activity was expressed against virus-infected fibroblasts. Using various biophysical and biochemical cell-separation methods, it was found that the effector cell active against both the xenogeneic tumor cells and virus-infected fibroblast belonged to the mononuclear phagocyte system. The indications are that at least two subpopulations of the blood monocytes, differing perhaps in maturation or clonal derivation, express NC-activity.     

Peritoneal and splenic B-1 cells are separable by phenotypic, functional, and transcriptomic characteristics

B-1 cells constitute a distinct B cell population with unique phenotypic and functional characteristics. Although the origin of B-1 cells remains controversial, B-1 cells in different locations are generally considered to be part of the same pool. To determine the validity of this assumption, we examined peritoneal and splenic B-1 cells isolated by flow cytometric cell sorting from normal mice for several features. We found that splenic B-1 cells differ from peritoneal B-1 cells in terms of surface antigen expression, viability ex vivo, immunoglobulin secretion in vitro, stimulated cell cycle progression, and expression of Notch family, Notch-dependent, and Notch-associated genes. These results indicate that splenic and peritoneal B-1 cells are not the same and thus dispute the notion that B-1 cells are uniform, and may suggest that different subpopulations of B-1 cells arise separately, home individually, and/or are heavily influenced by local environmental factors.     

Phenotype,and migration properties of three major subsets of tissue homing T cells in sheep

T cells show a bias in their migration pathways: some T cells preferentially migrate to peripheral lymph nodes (LN), some to mucosal tissues, and some to peripheral tissues such as skin. These recirculation pathways were examined in sheep by collecting lymph draining into and out of peripheral and intestinal LN, and using fluorescent dyes to trace the recirculation of the lymph cells. Monoclonal antibodies (mAb) to α4, β1, and β7 integrins, and L-selectin, were used to define three major populations of recirculating T cells. Naive-type T cells (L-selectin⁺, α4β1^lo β7^lo) migrated preferentially through peripheral LN. Two memory populations could be defined: α4β1^hi β7⁻ and α4β7^hiβ1^lo. α4β1^hi β7⁻ T cells were present in lymph draining from the skin. T cells migrating preferentially through intestinal LN were α4β7^hi β1^lo. Consistent with this migration pattern, the endothelial receptor for α4β7, mucosal addressin cell adhesion molecule-1 (MAdCAM-1) was detected on high endothelial venules within intestinal LN and Peyer's patches, but only weakly on high endothelial venules within peripheral LN. Thus, there are at least three easily definable subsets of T cells, based on integrin expression, which show distinct migration preferences.     

人γδT细胞表型与功能特征的探讨

目的比较观察人外周血PBMCs和CBMCs中αβT和γδT细胞的表型与功能特征,进一步了解γδT细胞在免疫应答中的作用。方法分离正常人PBMCs及脐带血CBMCs,检测表面分子的表达。PMA+Ionomycin刺激PBMCs或CBMCs后,利用流式细胞术(FCM)检测其细胞因子的产生以及初始/记忆细胞标记的表达。结果与αβT细胞相比,γδT细胞高表达CD45RO,低表达CD25和CCR7;与CBMCs中γδT细胞相比,PBMCs中γδT细胞表达CD45RO升高,CD45RA与CD25降低。细胞因子表达的结果表明,与αβT细胞相比,γδT细胞分泌大量IFN-γ和TNF-α,较少分泌IL-2,且IFN-γ+细胞主要为CD45RA-CD62L-CCR7-;与PBMCs中γδT细胞不同,体外刺激CBMCs中γδT细胞后,表达IFN-γ数量较低,且IFN-γ+细胞主要为CD45RA+CD62L-CCR7-/+。结论PBMCs与CBMCs中αβT和γδT细胞的表型与功能均存在差别,记忆性γδT细胞的增加可能与其活化和免疫应答的作用相关。     

The regulation of self-reactive B cells

Self-reactive B cells are eliminated in a series of checkpoints that are triggered by antigen binding. Recent reports have shown that in addition to the processes of elimination at the immature B-cell stage, B-cell anergy and regulation of T-cell help, self-reactive cells are also controlled by follicular competition, Fas-mediated elimination by T cells and censoring in the germinal centres. Each checkpoint operates at a threshold that reflects the need to maintain immune diversity at the same time as suppressing autoimmune disease. Analysis of the motheaten mutation has given a direct demonstration of how such thresholds can be modulated by genetic effects.