Reinvestigating the Role of IgM in Rabies Virus Postexposure Vaccination

B cells secreting IgG antibodies, but not IgM, are thought to be solely responsible for vaccine-induced protection against rabies virus (RABV) infections in postexposure settings. In this report, we reinvestigated the potential for IgM to mediate protection in a mouse model of RABV vaccination. Immunocompetent mice immunized with an experimental live replication-deficient RABV-based vaccine produced virus neutralizing antibodies (VNAs) within 3 days of vaccination. However, mice unable to produce soluble IgM (sIgM^−/−) did not produce VNAs until 7 days postimmunization. Furthermore, sIgM^−/− mice were not protected against RABV infection when challenged 3 days postimmunization, while all wild-type mice survived challenge. Consistent with the lack of protection against pathogenic RABV challenge, approximately 50- to 100-fold higher viral loads of challenge virus were detected in the muscle, spinal cord, and brain of immunized sIgM^−/− mice compared to control mice. In addition, IgG antibody titers in vaccinated wild-type and sIgM^−/− mice were similar at all time points postimmunization, suggesting that protection against RABV challenge is due to the direct effects of IgM and not the influence of IgM on the development of effective IgG antibody titers. In all, early vaccine-induced IgM can limit dissemination of pathogenic RABV to the central nervous system and mediate protection against pathogenic RABV challenge. Considering the importance for the rapid induction of VNAs to protect against RABV infections in postexposure prophylaxis settings, these findings may help guide the development of a single-dose human rabies vaccine.     

Imatinib treatment induces CD5+ B lymphocytes and IgM natural antibodies with anti-leukemic reactivity in patients with chronic myelogenous leukemia

Imatinib mesylate is a first line treatment of Chronic Myelogenous Leukemia and of a rare form of gastrointestinal stromal cancer, where the response to the drug is also linked to the immune system activation with production of antineoplastic cytokines. In this study, forty patients in the chronic phase of disease, treated with imatinib mesylate, were analyzed. Bone marrow aspirates were drawn at diagnosis, after 3, 6, 12, 18 months for haematological, cytofluorimetric, cytogenetic, biomolecular evaluation and cytokine measurement. Responder and non responder patients were defined according to the European LeukemiaNet recommendations. In responder patients (n = 32), the percentage of bone marrow CD20⁺CD5⁺sIgM⁺ lymphocytes, and the plasma levels of IgM, were significantly higher, at 3 months and up to 9 months, than in non responders. These IgM reacted with O-linked sugars expressed by leukemic cells and could induce tumor cell apoptosis. In responeìder patients the stromal-derived factor-1 and the B-lymphocyte-activating factor of the tumor necrosis factor family significantly raised in the bone marrow after imatinib administration, together with the bone morphogenetic proteins-2 and −7. All patients with high number of CD20⁺CD5⁺sIgM⁺ cells and high stromal-derived factor-1 and B lymphocyte activating factor levels, underwent complete cytogenetic and/or molecular remission by 12 months. We propose that CD20⁺CD5⁺sIgM⁺ lymphocytes producing anti-carbohydrate antibodies with anti-tumor activity, might contribute to the response to imatinib treatment. As in multivariate analysis bone marrow CD20⁺CD5⁺sIgM⁺ cells and stromal-derived factor-1 and B-lymphocyte-activating factor levels were significantly related to cytogenetical and molecular changes, they might contribute to the definition of the pharmacological response.     

Selective expression of murine lymphocyte alloantigens controlled by the X-chromosome

Alloantisera specific to X-chromosome linked lymphocyte membrane antigens (Ly-X) were prepared by immunizing F1 male mice with identical F1 female lymphocytes. Independent B cell specific (anti Lyb-X) and T cell specific (anti Lyt-X) antibodies were detected. The Lyt-X antigen was expressed on Lyt-2⁺, 3⁺, and on Tla^–, Lyt-1⁺, 2⁺, 3⁺ T cell subpopulations. The problem of X-chromosome inactivation and the relationship ofH-2-linkedIr genes and Ia antigens, with X-linkedIr genes and lymphocyte alloantigens are discussed.     

Rabbit lymphocytes with receptors for IgM. I. The development of receptors on lymphocytes following intravenous injection of antigen.

Under conditions optimal for detection of receptors for IgM (RFcμ) on human lymphocytes, RFcμ⁺ lymphocytes were not found in any of the tissues of nonimmune rabbits. However, 1 day after iv immunization with alum-precipitated keyhole limpet hemocyanin (KLH) or polymerized human IgG (pol-Ig), rabbit peripheral blood (PB) and spleen (S) demonstrated a significant percentage of lymphocytes (10%) with RFcμ. At 3 days after immunization there was a further increase in RFcμ⁺ lymphocytes (10–13%). By 6 days, however, the percentage of lymphocytes bearing receptors for IgM had returned nearly to zero. Pronase treatment was found to increase expression of RFcμ at 1 and 3 days in pol-Ig-primed tissues (up to 25%) but not in KLH-primed tissues. The percentage of RFcμ⁺ lymphocytes in tissues remained low at 6 days even after Pronase treatment. This time sequence of development of RFcμ⁺ cells after immunization seems interesting in the light of the findings of others that human lymphocytes with receptors for IgM are responsible for help in the PWM-induced differentiation of B cells to plasma cells.     

Changing behavior of surface immunoglobulin on mouse B lymphocytes during immune development: I. LPS-induced changes in the lateral mobility of B lymphocyte surface immunoglobulins on two populations which express different surface immunoglobulin phenotypes

The redistribution of surface membrane immunoglobulin molecules (sIg) was studied in two functionally distinct populations of mouse splenic B lymphocytes, namely, those bearing membrane IgM(IgG^?) and those bearing IgG. Brief exposure to mitogenic doses of bacterial lipopolysaccharide (LPS) produced direct but differential effects on the subsequent ability of specific antibodies to induce this redistribution on each cell type. Studied as a function of temperature, antibody-induced redistribution of sIgM on cells previously exposed to LPS was observed to occur at temperatures lower than the temperatures required for similar sIgM redistribution on lymphocytes not exposed to LPS. In contrast, mitogen-treated sIgG⁺ cells demonstrated an opposite and long-lasting effect (at least 40 hr), requiring higher temperatures to allow sIgG movement comparable to that seen on untreated sIgG-bearing lymphocytes. Thus, we conclude that LPS interacts with both IgM⁺(IgG^?) and IgG⁺ lymphocytes, but that such interactions produced different membrane effects on each B-cell subset. This membrane change can therefore be useful as a quasi-functional differentiation marker. Furthermore, differences in sensitivity to cellular activation by LPS seen between sIgM-bearing (sIgG^?) and sIgG-bearing B cells may be a reflection of such direct, although different, membrane effects.     

Circulating IgM Requires Plasma Membrane Disruption to Bind Apoptotic and Non-Apoptotic Nucleated Cells and Erythrocytes

Autoimmunity is associated with defective phagocytic clearance of apoptotic cells. IgM deficient mice exhibit an autoimmune phenotype consistent with a role for circulating IgM antibodies in apoptotic cell clearance. We have extensively characterised IgM binding to non-apoptotic and apoptotic mouse thymocytes and human Jurkat cells using flow cytometry, confocal imaging and electron microscopy. We demonstrate strong specific IgM binding to a subset of Annexin-V (AnnV)⁺PI (Propidium Iodide)⁺ apoptotic cells with disrupted cell membranes. Electron microscopy studies indicated that IgM⁺AnnV⁺PI⁺ apoptotic cells exhibited morphologically advanced apoptosis with marked plasma membrane disruption compared to IgM^-AnnV⁺PI⁺ apoptotic cells, suggesting that access to intracellular epitopes is required for IgM to bind. Strong and comparable binding of IgM to permeabilised non-apoptotic and apoptotic cells suggests that IgM bound epitopes are ''apoptosis independent'' such that IgM may bind any cell with profound disruption of cell plasma membrane integrity. In addition, permeabilised erythrocytes exhibited significant IgM binding thus supporting the importance of cell membrane epitopes. These data suggest that IgM may recognize and tag damaged nucleated cells or erythrocytes that exhibit significant cell membrane disruption. The role of IgM in vivo in conditions characterized by severe cell damage such as ischemic injury, sepsis and thrombotic microangiopathies merits further exploration.     

Characterization of T-lymphocyte subpopulations infiltrating primary breast cancer

Summary Characterization of T-lymphocyte subpopulations adjacent to and infiltrating the primary tumor of breast cancer was carried out using a direct immunofluorescence procedure with the antibodies anti-(Leu-2a) for suppressor/cytotoxic (CD8⁺) and anti-(Leu-3a) for helper/inducer (CD4⁺) T-lymphocytes. Fifty-six primary malignant tumors with lymphoid infiltration were studied. The majority (58.9%) were infiltrating duct carcinoma. There were metastases to axillary lymph nodes in 6.67% of the patients. Massive lymphoid infiltration (>40 lymphocytes per ×400 microscopic field) was found in 19.6% of the tumors and moderate infiltration (20–40 lymphocytes per field) in 51.8%. In all the tumors studied there was a reversed CD4⁺/CD8⁺ ratio as compared to that found in normal peripheral blood. In 66.1% the CD4⁺/CD8⁺ ratio (helper/suppressor) was less than 1.0. The reversed ratio was due to a significant decrease in the number of helper cells (P<0.0005). The most significant drop was in the stroma area (P<0.0001) as well as in the tumor tissue (P=0.001). Of particular interest was the significant positive correlation between the age of the patients and an increased number of CD4⁺lymphocytes in the stroma (P=0.02). Significant negative correlations were found between a reduced number of CD4⁺ lymphocytes or CD4⁺/CD8⁺ ratio and several histological parameters: tumor diameter, pleomorphism, nucleus/cytoplasm ratio. There was also a significant positive correlation between the total number of CD8⁺ lymphocytes infiltrating the tumor tissue and the number of axillary lymph nodes with metastatic disease (P=0.03). It is suggested that the reversed ratio of CD4⁺/CD8⁺ lymphocytes may significantly affect the host/tumor immune surveillance.     

肺癌患者外周血T淋巴细胞分型与抗核抗体之间的关系研究

摘要 目的：研究肺癌患者外周血T淋巴细胞分型与抗核抗体之间的关系。方法：选择2019年1月到2021年6月在我院接受治疗的肺癌患者81例作为研究组,并选择同期健康志愿者81例作为对照组,检测并比较两组患者外周血CD4⁺、CD8⁺和CD4⁺/CD8⁺淋巴细胞比例,以及抗核抗体血清滴度。比较不同抗核抗体、年龄、性别、TNM分期、肿瘤分化程度以及病理类型肺癌患者外周血CD4⁺、CD8⁺和CD4⁺/CD8⁺淋巴细胞比例。结果：（1）肺癌患者外周血CD4⁺和CD4⁺/CD8⁺淋巴细胞比例显著低于对照组,而CD8⁺淋巴细胞比例显著高于对照组（P<0.05）;（2）III+IV肺癌患者外周血CD4⁺、和CD4⁺/CD8⁺淋巴细胞比例均显著低于I+II肺癌患者,而CD8⁺淋巴细胞比例均显著高于I+II肺癌患者（P<0.05）;（3）小细胞肺癌患者外周血CD4⁺、和CD4⁺/CD8⁺淋巴细胞比例均显著低于非小肺癌患者,而CD8⁺淋巴细胞比例均显著高于非小肺癌患者（P<0.05）;（4）肺癌患者抗核抗体血清滴度显著高于对照组（P<0.05）;（5）抗核抗体阳性患者CD4⁺和CD4⁺/CD8⁺淋巴细胞亚群比例均显著低于抗核抗体阴性患者,而CD8⁺淋巴细胞亚群比例显著高于抗核抗体阴性患者（P<0.05）。结论：肺癌患者外周血T淋巴细胞亚群表达异常,并且其表达水平可能与抗核抗体滴度有关。     

The role of S100A4 protein in anticancer cytotoxicity: its presence is required on the surface of CD4+CD25+PGRPs+S100A4+ lymphocyte and undesirable on the surface of target cells

S100A4 is a Ca²⁺-binding protein that performs an important role in metastasis. It is also known for its antitumor functions. S100A4 is expressed by a specialized subset of CD⁴⁺CD²⁵⁺ lymphocytes and is present on those cell's membranes along with peptidoglycan recognition proteins (PGRPs). There, by interacting with major heat shock protein Hsp70, S100A4 plays an important cytotoxic role. The resulting stably formed complex of PGRPs, S100A4 and Hsp70 is required for the identification and binding between a lymphocyte and a target cell. Here, we investigated the S100A4 functions in CD⁴⁺CD²⁵⁺PGRPs⁺S100A4⁺ lymphocyte cytotoxicity against target cells. We demonstrated that those lymphocytes do not form a stable complex with the tumor target cells that themselves have S1004A on their surface. That observation can be explained by our finding that S100A4 precludes the formation of a stable complex between PGRPs, S100A4 (on the lymphocytes’ surface), and Hsp70 (on the target cells’ surface). The decrease in S100A4 level in CD⁴⁺CD²⁵⁺PGRPs⁺S100A4⁺ lymphocytes inhibits their cytotoxic activity, while the addition of S100A4 in the medium restores it. Thus, the resistance of target cells to CD⁴⁺CD²⁵⁺PGRPs⁺ S100A4⁺ lymphocyte cytotoxicity depends on their S100A4 expression level and can be countered by S100A4 antibodies.     

Two monoclonal antibodies highly specific for the blood group N determinant

Two monoclonal IgM antibodies, 179K and 35/5F, obtained following immunization of mice with A₂,MN or O,MN human erythrocytes, agglutinate NN and MN red cells strongly, and MM erythrocytes weakly. As shown by hemagglutination inhibition and solid phase ELISA, both antibodies are highly specific for the blood group N determinant. They react with N glycoprotein, its amino-terminal glycopeptides and with Ss glycoprotein (glycophorin B), which carries the blood group N determinant. They fail to react with M glycoprotein, M glycoprotein-derived glycopeptides, or with internal glycopeptides derived from N glycoprotein. Reaction of the antibodies with N glycoprotein is abolished by desialylation, periodate oxidation/borohydride reduction, orN-acetylation of the glycoprotein. Thus, the antibodies are specific for an epitope which includes sialylated oligosaccharide chain(s) and is located in the region of the amino-terminal leucine residue of N glycoprotein. MMU^– erythrocytes, lacking both blood group N and Ss glycophorin are non-reactive. Agglutination of MMU⁺ erythrocytes by the anti-N antibodies occursvia interaction with glycophorin B and correlates with the Ss phenotype of red cells MM,S erythrocytes are usually more strongly, agglutinated than MM,ss cells. The agglutination of MM erythrocytes decreases markedly as the pH is increased from 6 to 8, while agglutination of NN red cells is much less affected by shifts in pH over this range. As a result, both monoclonal antibodies are highly anti-N specific typing reagents when the agglutination assay is carried out at pH 8.     

INHIBITION OF FERTILIZATION IN FUCUS (PHAEOPHYCEAE) BY A MONOCLONAL ANTIBODY THAT BINDS TO DOMAINS ON THE EGG CELL SURFACE1

Fertilization in the brown alga Fucus serratus L. involves interactions between sperm and eggs and in species-specific. Recent results with monoclonal antibodies(MAbs FS4 and FS5) that recognize glycoproteins on the Fucus egg cell surface have shown that different sets of glycoproteins are organized into distinct domains. Thus, regions on the egg surface are FS4⁺FS5^? and FS4^?FS5⁺, and some smaller regions are FS4⁺FS⁺. To determine functional differences between these domains, MAbs FS4 and FS5 were included in a fertilization assay, Purified FS5 antibody, which is an immunoglobulin class M (IgM), inhibited fertilization, whereas FS4 IgM had no effect, Fragment antigen-binding fragment, which suggests that the effects were not due to steric hindrance by large IgM molecules or to cross-linking of receptors. FS5 inhibited fertilization in both F. serratus and F. vesiculosus; therefore, its effect was not species-specific, Thus we show that there is functional heterogeneity of the Fucus egg cell surface and compare our results to previous reports on inhibitory effects of lectins, Overall, the evidence suggests that there may be two levels of interaction between gametes in Fucus involoving nonspecific and species-specific binding.     

Heat Shock Cognate Protein 71-Associated Peptides Function as an Epitope for Toxoplasma gondii-Specific CD4+ CTL

HLA-DR-restricted CD4⁺ cytotoxic T-lymphocyte (CTL) lines specific for Toxoplasma gondii (T. gondii)-infected melanoma cells have been established from peripheral blood lymphocytes (PBLs) of a patient with chronic toxoplasmosis. The role of heat shock cognate protein (HSC) 71 in antigen (Ag) processing and presentation of T. gondii-infected melanoma cells to these CD4⁺ CTL lines was investigated. A human melanoma cell line (P36) pulsed with T. gondii-infected P36 cell-derived HSC71 was lysed by a T. gondii-specific CD4⁺ CTL line (Tx-HSC-1). The Tx-HSC-1 also killed T. gondii-infected P36 cells. The lytic activity of Tx-HSC-1 against P36 cells pulsed with T. gondii-infected P36 cell-derived HSC71 was inhibited by monoclonal antibodies (mAbs) against HSC71. Anti-human leukocyte antigen (HLA)-DR mAb also partially blocked the lytic activity, whereas anti-HLA-A,B,C mAb did not block the lytic activity. In addition, a flow cytometric analysis with these specific mAbs against HSC71 showed HSC71 to be expressed on the cell surface of T. gondii-infected P36 cells as well as uninfected P36 cells. These data indicate that HSC71 molecules are expressed on human melanoma cell line P36, and that HSC71 may play a potential role in Ag presentation and processing of T. gondii-infected P36 cells to CD4⁺ CTL.     

Antibacterial activity of human mononuclear leukocytes againstStaphylococcus aureus

Human mononuclear leukocytes killStaphylococcus aureus cellsin vitro. The killing of the bacteria takes place even in the absence of antibodies. The presence of antibodies (in an autologous inactivated serum) usually enhances the antibacterial activity of mononuclear leukocytes. In some cases, however, this activity is markedly decreased by the serum, probably depending of the spectrum of antibodies contained in the serum. The antibacterial activity of mononuclear leukocytes is mostly due to monocytes because their depletion causes substantial drop or the activity disappearance. We failed to demonstrate in the case ofS. aureus the antibacterial cytotoxicity of T lymphocytes described by some authors dealing with Gram-negative bacteria. Large differences in the structure of the bacterial cell wall underlie apparently the different sensitivity of G⁺ and G⁻ bacteria to some protective mechanisms of the host. In the antibacterial assay againstS. aureus, electron microscopy revealed a maximal activation of monocytes which phagocytized the bacteria although extracellular killing is not excluded. Electronoptical findings point also to a possible participation of NK cells in the antibacterial cytotoxicity againstS. aureus.     

Analysis of peripheral blood lymphocyte subsets and prognosis in patients with septic shock

The purpose of the study is to study the relationship between peripheral blood lymphocyte subset proportion and prognosis in patients with septic shock. Fifty‐two patients with septic shock, admitted to the intensive care unit between March 2007 and December 2010, were enrolled in this study. Peripheral blood lymphocyte subset proportions were measured using flow cytometry. The percentage of CD3⁺CD4⁺ T lymphocytes and CD19⁺ lymphocytes, CD4⁺/CD8⁺ T cell ratio were substantially lower in patients with septic shock compared to the control group (P < 0.01). The percentage of CD3⁺CD8⁺ T lymphocytes did not differ significantly between the two groups (P > 0.05). The percentage of CD16⁺CD56⁺ lymphocytes was higher in patients with septic shock than in the control group (P < 0.01). Compared with the survivor group, the percentage of CD3⁺CD4⁺ T lymphocytes and CD19⁺ lymphocytes, CD4⁺/CD8⁺ T cell ratio were clearly lower in the non‐survivor group (P < 0.01). There was no difference in the percentage of CD3⁺CD8⁺ T lymphocytes between the non‐survivor and survivor groups (P > 0.05). The percentage of CD16⁺CD56⁺ lymphocytes was higher in the non‐survivor group than in the survivor group (P < 0.05). The total maximum SOFA score and the delta SOFA score were much higher in the non‐survivor group than in the survivor group (P < 0.01). Immune imbalance occurs in patients with septic shock. Peripheral blood lymphocyte subset proportion and SOFA scores can be used to assess the treatment and prognosis of septic shock.     

Heterogeneity of B cell clones: immunoglobulin-secreting subsets

Staphylococcus aureus Cowan I bacteria (SpA CoI) is known to be a polyclonal B-cell activator of human lymphocytes. In this study, we investigated which of the B-cell subsets SpA CoI could stimulate and induce immunoglobulin (Ig) production. B-Cell subsets were separated from peripheral blood and tonsil lymphocytes by rosette formation with E, EA_IgG, EAC, anti-Ig-conjugated ox erythrocytes (OE-anti-Ig), and protein A-conjugated OE (OE-Pro A), or on a bovine serum albumin (BSA) discontinuous density gradient. The cells responding to SpA CoI included E^?, C3 receptor-positive (C3R⁺), Fc receptor-negative (FcR^?), and surface Ig-positive (SIg⁺) B-cell subsets. These B-cell populations responded well to SpA CoI and produced significant amounts of IgG, IgM, and a lesser amount of IgA. Among SIg⁺ B cells, IgG, IgA, and IgM⁺ B-cell subsets responded to SpA CoI and produced large amounts of Ig belonging to each corresponding Ig class. IgD⁺ B cells failed to produce Ig of any class, except for minimal amounts of IgG and IgM. While both the protein A receptor-positive (Pro A · R⁺) and negative (Pro A · R^?) cells responded well to SpA CoI, Pro A · R⁺ B cells produced IgG mainly and Pro A · R^? B cells produced IgM. Fractionation of B cells on a BSA gradient revealed that comparatively small-sized and denser B-cell subsets responded well to SpA CoI and produced every class of Ig.     

Regulation of Promoter and Intron Enhancer Activity in Immunoglobulin Heavy-Chain Genes during B-Cell Differentiation

Chloramphenicol acetyltransferase (CAT) transgenic mice, in which the transgene is regulated by the VH promoter and heavy-chain intron enhancer (Eμ), were examined to investigate the variation of activity of these cis-acting elements during the late stage of B-cell development. CAT enzyme activity decreased when resting B cells were stimulated through B-cell receptors (BCR) with goat anti-mouse IgM antibodies in vitro. On the other hand, when these B cells were stimulated by lipopolysaccharide (LPS) in vitro, they showed enhanced CAT activity, accompanied by an increase in the number of CD43⁺ B220⁺ cells (pro-plasma and plasma cells). In addition, the CAT activities in CD43⁺ B220⁺ and PNA^hi B220⁺ cells from immunized mice were higher than those in CD43^? B220⁺ and PNA^lo B220⁺ cells, respectively. These results suggest that the activity of Eμ in the context of VH promoter was transiently down-regulated by stimulation through the BCR but enhanced at the pro-plasma and plasma stages.     

Passive Immunization with Hypochlorite-oxLDL Specific Antibodies Reduces Plaque Volume in LDL Receptor-Deficient Mice

Aims

New strategies to overcome complications of cardiovascular diseases are needed. Since it has been demonstrated that atherosclerosis is an inflammatory disease, modulation of the immune system may be a promising approach. Previously, it was suggested that antibodies may confer protective effects on the development of atherosclerosis. In this study, we hypothesised that passive immunization with anti-oxLDL IgM antibodies specific for hypochlorite (HOCl) may be athero-protective in mice.

Methods and Results

Monoclonal mouse IgM antibodies were produced and the antibody with specificity for hypochlorite-oxLDL (HOCl-oxLDL) (Moab A7S8) was selected. VH sequence determination revealed that Moab A7S8 is a natural IgM antibody. Atherosclerosis in LDLr^−/− mice was induced by a perivascular collar placement around the right carotid artery in combination with feeding a high-fat diet. Subsequently, the mice were treated every six days with 500 µg Moab A7S8, non-relevant IgM or with PBS and the carotid arteries and aortic roots were studied for atherosclerosis. Passive immunization with this Moab A7S8 resulted in a significant reduced plaque volume formation in LDLr^−/− mice when compared with PBS treatment (P = 0.002 and P = 0.035). Cholesterol levels decreased by 20% when mice were treated with Moab A7S8 compared to PBS. Furthermore, anti-oxLDL specific IgM and IgG antibody production increased significantly in the Moab A7S8 treated mice in comparison with PBS treated mice.

Conclusion

Our data show that passive immunization with a natural IgM antibody, directed to HOCl-oxLDL, can reduce atherosclerotic plaque development. We postulate that specific antibody therapy may be developed for use in human cardiovascular diseases.     

A pilot study evaluating the utility of commercially available antibodies for flow cytometric analysis of <Emphasis Type="Italic">Panthera</Emphasis> species lymphocytes

Background

The immune response against tuberculosis in lions is still poorly defined and our understanding is hampered by the lack of lion specific reagents. The process for producing antibodies against a specific antigen is laborious and not available to many research laboratories. As the search for antibody cross-reactivity is an important strategy for immunological studies in veterinary medicine, we have investigated the use of commercially available antibodies to characterize T cell subsets in African lions (Panthera leo).

Results

Commercially available antibodies were screened and investigated the influence of two different sample processing methods, as well as the effect of time delay on cell surface marker expression on lion lymphocytes. Using commercially available antibodies, we were able to identify CD4⁺, CD5⁺, CD8⁺, CD14⁺, CD25⁺, CD44⁺ and CD45⁺ T lymphocytes in samples obtained by density gradient centrifugation as well as red cell lysis of lion whole blood. Two distinct lymphocyte populations, which differed in size and phenotype, were observed in the samples processed by density gradient centrifugation.

Conclusion

Commercially available antibodies are able to differentiate between T lymphocyte subsets including immune effector cells in African lion whole blood, and possibly give insight into unique specie phenotypes.

     

Dietary omega-3 fatty acids enhance the B1 but not the B2 cell immune response in mice with antigen-induced peritonitis

The effects of omega-3 fatty acids on the adaptive immune response have mainly been analysed in vitro with varying results. How omega-3 fatty acids affect the adaptive immune response in vivo is largely unknown. This study examined the effects of dietary fish oil on the adaptive immune response in antigen-induced inflammation in mice, focusing on its effects on B cells and B cell subsets. Mice were fed a control diet with or without 2.8% fish oil, immunized twice with methylated BSA (mBSA) and peritonitis induced by intraperitoneal injection of mBSA. Serum, spleen and peritoneal exudate were collected prior to and at different time points after induction of peritonitis. Serum levels of mBSA-specific antibodies were determined by ELISA and the number of peritoneal and splenic lymphocytes by flow cytometry. The levels of germinal center B cells and IgM⁺, IgG⁺ and CD138⁺ cells in spleen were evaluated by immunoenzyme staining. Mice fed the fish oil diet had more peritoneal B1 cells, more IgM⁺ cells in spleen and higher levels of serum mBSA-specific IgM antibodies compared with that in mice fed the control diet. However, dietary fish oil did not affect the number of peritoneal B2 cells, splenic IgG⁺ or CD138⁺ cells or serum levels of mBSA-specific IgG antibodies in mice with mBSA-induced peritonitis. These results indicate that dietary fish oil can enhance the adaptive immune response, specifically the B1 cell response, which may lead to better protection against secondary infection as well as improvement in reaching homeostasis following antigenic challenge.     

Reactivities of Shark 19S and 7S IgM Antibodies to <Emphasis Type="Italic">Salmonella typhimurium</Emphasis>

LOWER vertebrates such as sharks can synthesize humoral antibodies in response to antigenic stimulation with a wide variety of antigens¹. Physicochemical studies have shown that sharks can synthesize both 19S and 7S immunoglobulins and that these two proteins belong to the same immunoglobulin class, which seems to be structurally homologous to IgM as defined for higher animals. Thus the shark immunoglobulins have been designated 19S IgM and 7S IgM^2–4. Because the predominant immunoglobulin (IgG) of most mammals is absent from sharks, the shark monomeric (7S) IgM might be functionally analogous to IgG. One example of the functional differences between IgM and IgG antibodies is the greater reactivity of the former in agglutination and bactericidal reactions^5,6. We have isolated and characterized functionally the relatively high levels of agglutinating antibodies which the nurse shark, Gingly-mostoma cirratum, synthesizes in response to Salmonella typhimurium “O” antigens.