Human lymphokine-activated killer cells suppress pokeweed mitogen-induced immunoglobulin synthesis.

The effect of human lymphokine-activated killer (LAK) cells on pokeweed mitogen (PWM) induced immunoglobulin synthesis by autologous peripheral blood mononuclear cells (PBMC) was studied. LAK cells induced by the in vitro culture with recombinant human interleukin-2 (IL-2) lysed PWM-activated autologous T cells and B cells, but did not lyse unstimulated lymphocytes. These effector cells which are capable of killing lymphoblasts were shown to express either CD16 surface markers. When CD8(+)-and CD16(+)-enriched cells isolated from the culture with IL-2 were added to cultures containing autologous PBMC and PWM, marked suppression of the IgG production was observed. In contrast, the control CD8(+)-and CD16(+)-enriched cells isolated from the culture without IL-2 showed a weak suppressive effect on PWM-induced IgG synthesis. These results suggest that LAK cells suppress immunoglobulin synthesis by the cytotoxic elimination of activated T cells and B cells.     

The suppressive effect of gammaglobulin preparations on in vitro pokeweed mitogen-induced immunoglobulin production.

The effect of the supplementation with several gammaglobulin (GG) preparations on the in vitro immunoglobulin synthesis of peripheral blood mononuclear cells (PBMC) from normal subjects stimulated with pokeweed mitogen (PWM) was studied. Among the GG preparations used in this study, immune serum globulin (ISG) demonstrated the most suppressive effect, and S-sulfonation and polyethylene glycol (PEG)-treated preparations also had a suppressive effect. However, the preparation of pepsin degradation had no suppressive effect. And because IgG F(ab')2 fragments also failed to induce the suppressive effect, it was considered to be triggered by the attachment of the Fc portion of GG to the corresponding membrane receptor. To determine the cellular targets, PBMC were fractionated into E-rosetting cells (T cells) and non E-rosetting cells (B cells). The suppressive effect was induced by pre-incubation of either T cells or B cells with the GG preparations for 1 h, at 37 degrees C in PWM-induced immunoglobulin (Ig) production. The failure of T cells pretreated with OKT8 monoclonal antibody and complement to induce the suppressive effect suggested that T8 positive T cells are one of the effector cells involved. The activation step of the suppressive effect was prostaglandin E2-independent, and as effector cells contain an Fc receptor which is sensitive to pronase, it was suggested that monocytes were not involved in this activation process. Our observations further suggested that the Ig effects of GG therapy are not limited to antibody transfer, since GG preparations also suppress directly the differentiation of B cells and induce suppressor T cells in in vitro immunoglobulin production stimulated with PWM.     

Studies on human blood lymphocytes with iC3b (type 3) complement receptors. II. Characterization of subsets which regulate pokeweed mitogen-induced lymphocyte proliferation and immunoglobulin synthesis.

Human blood lymphocytes that express Type 3 complement receptors (CR3) can be divided into a major subset with high density Fc receptors for IgG (FcR) identified with the monoclonal antibody Leu 11 and two minor subsets which display either CD8 (Leu 2) or CD4 (Leu 3) markers. We isolated CR3+ lymphocyte subsets and examined them for regulatory effects on pokeweed mitogen (PWM) stimulated cells. The FCR CR3+ cell suppressed PWM-induced proliferation and Ig production. Pretreatment of these lymphocytes with immune complexes was required to suppress proliferation, but not IgG production. The CR3+ Leu 2+ FCR- subset also had suppressive activity, but this effect was not observed unless the CR3+ Leu 3+ enriched subset was removed. In fact, the CR3+ Leu 3+ enriched subset enhanced IgG synthesis. Brief exposure of CR3+ lymphocytes to recombinant interleukin 2, recombinant alpha-interferon, but not gamma-interferon, markedly enhanced the inhibitory effect. Time course studies and a comparison of inhibition of Ig synthesis with natural killer cell activity suggested that CR3+ lymphocytes act shortly after lymphocytes are exposed to PWM and that Ig production was regulated by suppression rather than cytotoxicity. These CR3+ lymphocyte subsets may have broad antigen non-specific effects on immunoglobulin synthesis.     

Suppression of in vitro immunoglobulin synthesis by CD16(Leu11a)+ CD56 (NKH1,Leu19)+non-T lineage NK cells; lack of suppression of cells from immunodeficient patients

We examined the effect of both CD3-CD16(Leul la)+CD56(NKH1,Leu19)+ non-T lineage natural killer (NK) cells and CD3+CD8+CD16-CD56+ T lineage NK cells on B cell proliferation and differentiation. Fluorescence-activated cell sorter (FACS) purified CD16+CD56+ cells suppressed pokeweed mitogen (PWM) induced immunoglobulin synthesis. However, the T lineage NK cells tended to suppress immunoglobulin synthesis only when CD8+ cells were eliminated from the culture, and even then CD16+ NK cells suppressed antibody production more efficiently than did CD3+CD8+ NK cells. CD16+ NK cells did not suppress B cell proliferative responses to several mitogens. CD16+ NK cells from patients with Wiskott-Aldrich syndrome, who showed the high percentage of CD16+ NK cells, did not inhibit immunoglobulin synthesis. We concluded that non-T NK cells are the major immunoregulatory NK cells for immunoglobulin synthesis in normal immune systems, and that they suppress immunoglobulin synthesis through their action on B cell differentiation.     

Selective depletion of CD11c+CD11b+ dendritic cells partially abrogates tolerogenic effects of intravenous MOG in murine EAE

Intravenous (i.v.) injection of a soluble myelin antigen can induce tolerance, which effectively ameliorates experimental autoimmune encephalomyelitis (EAE). We have previously shown that i.v. myelin oligodendrocyte glycoprotein (MOG) induces tolerance in EAE and expands a subpopulation of tolerogenic CD11c⁺CD11b⁺ dendritic cells (DCs) with an immature phenotype having low expression of IA and co‐stimulatory molecules CD40, CD86, and CD80. Here, we further investigate the role of tolerogenic DCs in i.v. tolerance by injecting clodronate‐loaded liposomes, which selectively deplete CD11c⁺CD11b⁺ and immature DCs, but not CD11c⁺CD8⁺ DCs and mature DCs. I.v. MOG‐induced suppression of EAE was partially, yet significantly, blocked by CD11c⁺CD11b⁺ DC depletion. While i.v. MOG inhibited IA, CD40, CD80, CD86 expression and induced TGF‐β, IL‐27, IL‐10 production in CD11c⁺CD11b⁺ DCs, these effects were abrogated after injection of clodronate‐loaded liposomes. Depletion of CD11c⁺CD11b⁺ DCs also precluded i.v. autoantigen‐induced T‐cell tolerance, such as decreased production of IL‐2, IFN‐γ, IL‐17 and numbers of IL‐2⁺, IFN‐γ⁺, and IL‐17⁺ CD4⁺ T cells, as well as an increased proportion of CD4⁺CD25⁺Foxp3⁺ regulatory T cells and CD4⁺IL‐10⁺Foxp3^? Tr1 cells. CD11c⁺CD11b⁺ DCs, through low expression of IA and costimulatory molecules as well as high expression of TGF‐β, IL‐27, and IL‐10, play an important role in i.v. tolerance‐induced EAE suppression.     

Response of human T lymphocytes to phytohemagglutinin (PHA) after sequential depletion of monocytes, HLA-DR+, Leu11a+, and Leu7+ cells

The experiments presented in this paper deal with the question of whether there is an absolute requirement for alpha-naphtylacetate esterase (ANAE)-positive monocytes, HLA-DR+, Leu11a+, and/or Leu7+ cells to stimulate human peripheral blood T lymphocytes by phytohemagglutinin (PHA). Purified (p) T lymphocytes containing less than 0.1% ANAE-positive monocytes were isolated from human peripheral blood mononuclear cells (MNC) by sequential removal of carbonyl-iron phagocytic cells and of low-density cells by density gradient centrifugation and isolation of E-rosette-forming cells (E-RFC). These pT-cells were further depleted of HLA-DR+, Leu11a+, and/or Leu7+ cells using monoclonal antibodies and cell sorting. The T lymphocytes were stimulated by PHA in an ultra-micro culture in glass capillaries at a volume of 1 microliter or 2 microliters, containing 1000 cells per culture. With this method, the accessory cell requirement could be studied under limiting cell number conditions. The results show that pT-cells can be stimulated by PHA in the absence of ANAE-positive monocytes. No ANAE-positive monocytes were found in the culture after stimulation, indicating the lack of differentiation into ANAE-positive monocytes from ANAE-negative precursors. A rabbit antiserum against leukocytic pyrogen (LP, also containing anti-IL 1 activity) only reduced but did not abrogate the stimulation of pT-lymphocytes by PHA. Addition of adherent cells resulted in an enhancement or in an inhibition of the response of pT-lymphocytes to PHA, depending on cell concentration and culture time: The lower the number of cultured T lymphocytes and the shorter the culture time, the higher was the enhancing activity by additional adherent cells, and vice versa. Further purification of the pT-cells using monoclonal antibodies and cell sorting led to the finding that depletion of either HLA-DR+, Leu11a+, or Leu7+ from pT-cells only reduced but did not abrogate the stimulation of the pT-cells by PHA. However, in absence of HLA-DR+ and Leu7+ cells, the pT-lymphocytes totally failed to respond to PHA. This abrogation of the response was not observed when pT-cells were depleted of HLA-DR+ and Leu11a+ cells. In addition, T11+/HLA-DR- T lymphocytes isolated from E-RFC by positive selection in a cell sorter also responded to PHA.(ABSTRACT TRUNCATED AT 400 WORDS)     

Protective role of NK1.1+ cells in experimental Staphylococcus aureus arthritis.

In a model of Staphylococcus aureus-induced septic arthritis in C57Bl/6 mice we investigated the role of natural killer (NK) cells in the development of disease. Depletion of NK1.1+ cells was achieved by repeated injections of the PK136 antibody, whereas control mice received an irrelevant monoclonal antibody, O1C5.B2. Both groups of mice then received injections intravenously with 2 x 107 live S. aureus LS-1 secreting toxic shock syndrome toxin-1 (TSST-1). The mice were evaluated for 16 days with regard to weight, mortality and arthritis. Nine days after bacterial injection, 9/19 mice depleted of NK cells had developed arthritis compared with 1/17 in the control group (P = 0.01). The experiment was repeated twice with the same outcome. NK cell-depleted and control mice displayed the same degree of histopathological signs of arthritis at day 16. Depletion of NK cells did not affect uptake of bacteria by phagocytic cells in vitro, or bacterial clearance in vivo. In NK cell-depleted mice there was a tendency to increased levels of antibodies to TSST-1, whereas total immunoglobulin levels were similar to those in controls. NK cell depletion of non-infected mice did not affect the magnitude of inflammatory response during the T cell-dependent cutaneous DTH reaction to oxazolone, or during granulocyte-mediated inflammation. However, specific antibody responses to oxazolone were greatly increased in depleted animals. In conclusion, our study demonstrates that NK cells protect against arthritis during S. aureus infection. This outcome does not seem to be due to an influence on bacterial clearance, but could be due to an interaction with the host anti-inflammatory mechanisms.     

Prognostic role of CD11b+ myeloid-derived suppressor cells in oral squamous cell carcinoma

IntroductionMyeloid-derived suppressor cells (MDSCs) are critically involved in cancer immune suppression and MDSC density has been recognized as a robust prognostic biomarker. Here, we sought to characterize the densities and locations of CD11b⁺ MDSCs in primary oral squamous cell carcinoma (OSCC) and determine their prognostic significance.Material and methodsA total of 144 eligible OSCC samples from a tertiary referral oral cancer center were retrospectively collected. Intensities of CD11b⁺ MDSCs at the tumor center (CT) and invasive margin (IM) in OSCC samples were detected by immunohistochemistry and automatically quantified using Image J software. The optimal cutoff values for CD11b CT and CD11b IM were determined by X-tile based on overall survival. The associations between CD11b⁺ MDSCs and clinicopathological parameters were assessed by the χ² test. The prognostic value of CD11b⁺ MDSCs was evaluated by Kaplan-Meier plots, Cox regression analyses and receiver operating characteristics curves.ResultsHigh density of CD11b⁺ MDSCs at CT or IM was significantly associated with inferior overall and disease-free survival (Kaplan-Meir, p < 0.05, log-rank test). CD11b CT and CD11b IM were identified as independent prognostic predictors for patient survival. The prediction accuracy and specificity of CD11b CT and CD11b IM were superior to other prognostic parameters.ConclusionsOur data indicated that increased densities of CD11b⁺ MDSCs in CT and IM regions were significantly associated with poor prognoses, which might be novel prognostic factors for OSCC.     

Increased number of circulating Leu 11+ (CD 16) large granular lymphocytes and decreased NK activity during human ageing.

The phenotype and functional activity of circulating T and natural killer (NK) cells was investigated in a group of selected normal elderly donors in comparison with a group of normal young individuals. Old subjects exhibit a decline in circulating T cells and an impaired response to mitogens (Con A, PHA) associated with a relative increase in cells reacting with Leu 7 and Leu 11a monoclonal antibodies, directed against large granular lymphocytes with NK activity. The rise in circulating NK cells observed in the elderly was not associated with a concomitant increase in NK cytolytic activity against K 562 tumour cells, and time course kinetics of the cytotoxic reaction was similar to that observed in young subjects. When a greater than 95% pure population of Leu 11a+ cells from old individuals was sorted by flow cytometry and their functional cytotoxic activity examined, a significant decrease in NK cytotoxicity was detected. The target cell binding capacity of effector cells, morphologically evaluated at single cell level, did not differ in old and young subjects, even though bound cells from young donors have a higher lytic capacity. These data show that an increase in circulating NK granular lymphocytes occurs during human ageing, but suggest that in old subjects only a subset of NK cells is active in order to maintain a functional response similar to that observed in the young.     

Contribution of CR3, CD11b/CD 18 to cytolysis by human NK cells

The complement receptor CR3 molecule functions in direct intercellular contacts mediated by its beta chain, CD18. Similarly to the Fc receptor (CD16), CR3 is a marker of human natural killer cells. We have shown that opsonization of NK targets with iC3b leads to their increased lytic sensitivity. Opsonization could be achieved by incubating certain B and T cell lines in human serum. The expression of CR2 was a prerequisite for C3 fragment fixation. The CR2 negative cell line, P3HR1 could be opsonized by incubation in human serum when induced to express the EBV envelope glycoprotein gp350. C3b or iC3b could also be deposited artificially on cell surfaces by chemical coupling to surface reactive antibodies. Similarly to the function of macrophages and monocytes, contact with opsonized targets exclusively through the iC3b binding site of CR3 did not seem to trigger NK function. We attempted to clarify the functional role of other CR3 ligands. The beta chain of the molecule, CD18, was essential to the NK effect. The NK targets did not seem to interact with the beta-glucan binding epitope on the alpha chain of CR3, CD11b. On the other hand, the cytolytic function could be enhanced through this epitope with the appropriate ligand.     

Enhanced percentage of Leu M3+DR+ and Leu M3+CD25+ cells in newly diagnosed IDDM patients.

The percentage of Leu M3+DR+ and of Leu M3+CD25+ cells was determined by means of immunofluorescence analysis in a group of patients with insulin dependent diabetes mellitus (IDDM). Our results show that an increased percentage of these cells may occur in the early stage of the disease. These data provide evidence for a "phenotypical" activation of Leu M3+ cells at the onset of the disease and warrant future studies to evaluate the potential role of these cells in the pathogenesis of IDDM.     

Suppressor response in lepromatous leprosy patients: role of Leu 2a cells.

The contribution of non-specific suppressor mechanisms to the overall immunoregulatory defect observed in lepromatous leprosy was evaluated. Con A-induced suppression was assayed using the standard two-stage test in 27 lepromatous leprosy patients, 19 of them during the quiescent stage (LL) and eight during erythema nodosum lepromatosum (ENL). Lymphocytes from normal individuals react in this assay, yielding higher suppression as the numbers of Con A-induced suppressor cells (Leu 2a+ cells) increase. In contrast, two patterns of response were observed in both LL and ENL patients: those giving lower suppression as the number of suppressor cells increased (LL-A and ENL-A) and those responding with the normal pattern (LL-B and ENL-B). The abnormal dose-response profile was not related to the disease stage, as both ENL and LL patients were included in groups with normal or atypical response. Reaction of the potential suppressor cells with anti-Leu 2a antibody abolished suppression in LL-B and normals, whereas Con A-induced suppression was unchanged or higher in ENL-A, ENL-B and LL-A, indicating that in these patients Leu 2a+ cells interfered with the generation of Con A-induced suppression. The contribution of spontaneous suppression was examined and it was shown that suppressor activity in the absence of Con A stimulus was higher in ENL (both ENL-A and ENL-B) and LL-A. Thus, it appears that the occurrence of high spontaneous suppressor activity, probably related to in vivo activation, is associated with a relative inability to generate de novo suppression after Con A stimulation in these patients.     

Interleukin 2 induces appearance of LGL/Leu11+/K562 lytic cells in Leu11- low density peripheral blood mononuclear cell population

Low density Percoll fraction cells cultured with interleukin 2 (IL-2) showed a higher proportion of large granular lymphocytes (LGL) and higher K562 cytolytic activity, as compared to a culture lacking IL-2. Furthermore, in a negatively selected Leu11- population, derived from low density cells, cultured for 7 days in medium supplemented with lymphocyte (L) or recombinant (R) IL-2, there appeared LGL and Leu11+ cells. Moreover, some level of K562 lytic activity and higher proportion of DR+ and Tac+ cells was found as compared to lacking IL-2 culture. Cytofluorograph analysis of cells labelled with propidium iodide revealed that a proportion of the low density Leu11- starting cell population entered the growth cycle while cultured with IL-2. In addition was found that Leu11+ cells evolve during culture with IL-2 into population lacking in part this phenotype marker. The present work shows that precursors of K562 cytolytic cells lacking Leu11 antigen reside in low density cell fraction, and that they may differentiate in LGL/Leu11+ cells.     

Expression of CD11b (Leu15) antigen on CD3+, CD4+, CD8+, CD16+ peripheral lymphocytes. Estimation of CD3+8+11b+ and CD3+4-8-11b+ T-cell subsets using a single laser flow cytometer.

CD11b (Leu15) epitope is expressed on 20-30% of peripheral blood lymphocytes, including CD16+ large granular lymphocytes and CD8+ cells. This study confirms that 30% of CD8+ lymphocytes and virtually all CD16+ NK cells from healthy subjects express this determinant. In parallel, our data show that various proportions of CD3+4-8-, TCR-delta cytotoxic T lymphocytes and occasionally CD4+ lymphocytes subsets could also express this epitope. The CD8+11b+ phenotype is associated with suppression of T-cell proliferative response and has been extensively used to characterize suppressor T lymphocytes. Since about 25% of CD8 lymphocytes are non-T (CD3-) and express the CD16 NK antigen (CD8+16+3-), the expression of CD11b was also studied on CD8+3+ T-cell and CD8+16+ NK-cell subsets. To this end, we developed three methods using a flow cytometer equipped with a single laser and two fluorescence detectors. Results showed that T CD8+3+11b+ and NK CD8+16+11b+ lymphocytes account for 30% and 70% of CD8+11b+ cells respectively. Consequently, the CD8+3+11b+ phenotype would be more specific for suppressor T lymphocytes than the total CD8+11b+ phenotype which includes high proportions of CD16+ NK cells.     

CD8+ CD11+ suppressor cells in HIV-infected asymptomatic patients: effect on HIV-specific cytotoxicity.

CD3+CD8+CD11+ cells were present in the peripheral blood of patients infected with asymptomatic human immunodeficiency virus (HIV) in higher percentage (10-20%) than in normal individuals (3-5%) in this study. These cells, through the release of soluble factors, significantly suppressed the effector phase of anti-HIV cytotoxic activities, both human leukocyte antigen (HLA)-class I or class II restricted, and nonrestricted. The effectors were CD8+CD11-, CD4+ T cells, and CD16+ cells for HLA-class I, class II restricted, and nonrestricted cytotoxicities, respectively. The soluble factors also inhibited natural killer cell activity. Thus, this effect was neither HLA-restricted nor antigen-specific. These CD3+CD8+CD11+ cells may be an important immunopathogenic factor in HIV disease.     

黄芪多糖佐剂对脾脏NK细胞及NKT细胞的作用

目的观察脾脏NK细胞及NKT细胞在黄芪多糖（APS）发挥免疫佐剂功能的作用。方法使用鸡卵白蛋白（OVA）与APS经皮下免疫C57BL/6小鼠3次。末次免疫7～14d,取血清,使用ELISA观察OVA特异性抗体的含量;分离脾脏淋巴细胞,使用流式细胞仪检测NK和NKT细胞的百分比含量;使用PMA和Ionimycin刺激淋巴细胞,使用细胞内细胞因子染色的方法检测IFN-γ和IL-4的分泌情况。结果 APS组小鼠OVA特异性抗体含量明显高于OVA组小鼠（P〈0.05）,但小鼠脾脏内NK和NKT细胞的百分比含量与OVA组和正常小鼠差别不大（P〉0.05）。经PI刺激以后,APS组小鼠脾脏内NK细胞中IL-4＋细胞明显高于OVA组和正常组（P〈0.05）,且IFN-γ＋细胞的比例明显下降（P〈0.05）;虽然经过PI刺激以后,APS组小鼠脾脏内NKT细胞中IL-4＋细胞升高不明显,但是IFN-γ＋细胞的比例明显下降（P〈0.05）。结论 APS可以通过调节NK和NKT细胞的功能来促进体液免疫应答。     

Cells and mediators which participate in immunoglobulin synthesis by human mononuclear cells. III. Null cells secrete a factor(s) (human immunoglobulin synthesis/secretion-facilitating factor) that can replace the null cells in the synthesis of immunoglobulin by cultured B cells.

In the accompanying communication, it was demonstrated that the null cells, the TM cells, monocytes and PWM are all obligatory participants in the synthesis and secretion of immunoglobulins by human B cells in culture. Here we demonstrate that the null cells secrete a factor, referred to as human immunoglobulin synthesis/secretion-facilitating factor (HISFF) that can replace the null cells in the cultures. HISFF is distinct from the known T cell-derived interleukins. HISFF functions in an HLA-unrestricted fashion since it can facilitate the synthesis and secretion of immunoglobulins by allogeneic B cells. The null cells cultured with TM helper cells and PWM required monocytes in the culture in order to secrete HISFF. Furthermore, B cells cultured with TM cells in medium containing HISFF, monocyte-derived factors and PWM nevertheless required monocytes in order to respond to the HISFF signal. Thus, the monocyte plays a pivotal role in the secretion of and response to HISFF. Normal levels of immunoglobulin were synthesized even when HISFF was added to the cultures of B cells, TM cells and monocytes, in the presence of PWM, as late as day 6 of the 7 day culture. We conclude that the null cells participate in immunoglobulin synthesis by the B cells by secreting a soluble mediator, HISFF, capable of replacing the null cells in the culture; and that the HISFF signal is the last signal received by the B cell before it begins to synthesize and secrete immunoglobulins.     

In vitro IgM and IgM rheumatoid factor production in response to Staphylococcus aureus Cowan I and pokeweed mitogen: the contribution of CD5+ (Leu 1) B cells.

The relation between the percentage of circulating CD5+ CD20+ B cells and the ability to synthesize IgM and IgM rheumatoid factor (RF) in vitro in response to pokeweed mitogen (PWM) and Staphylococcus aureus Cowan I (SAC) was assessed in 21 healthy controls. CD5+ CD20+ cells ranged from 7.3 to 19.9% of total CD20+ B cells. By Spearman's rank correlation, there was an inverse relation between the percentage of CD5+ CD20+ B cells and IgM production in response to PWM (rs = -0.452, p less than 0.05) and a direct correlation with RF production in response to SAC (rs = 0.450, P less than 0.05). The percentage of CD5+ CD20+ B cells was not related to any serologic HLA-A, B, C or D antigen. Healthy individuals may be predisposed to producing IgM or autoantibodies based on the percentage of circulating CD5+ Cd20+ B cells.