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Background: Some ligands of pattern recognition receptors (PRR) are present on tumour cells. The role of PRR in signalling for cytokine and reactive oxygen intermediates (ROI) production by monocytes and monocyte-derived macrophages (MDM) stimulated with tumour cells was studied., Materials and Methods: Monocytes/MDM were pretreated with PRR ligands or anti-PRR monoclonal antibodies (mAbs) and stimulated with tumour cells. Cytokine secretion was measured by enzyme-linked immunoassay (ELISA) and ROI production by luminol-dependent chemiluminescence (CL)., Results: The ligands of scavenger receptor A (SR-A): (fucoidan, polyguanylic acid (polyG) and modified low density lipoproteins (LDL)) and B (SR-B) (native and modified LDL, phosphatidylserine (PdS)) and of mannose receptor (MR) (mannan), induced tumour necrosis factor alpha (TNF) and ROI (except LDL) release by monocytes. Production of TNF and interleukin-10 (IL-10) by MDM was stimulated by SR-A ligands and mannan. Tumour cell-induced TNF and IL-10 production by monocytes, but not MDM, was diminished by fucoidan and polyG, while ROI release was reduced by MR and SR-A ligands. Supplementation of tumour cells with modified LDL and PdS enhanced their stimulatory capacity. TNF and ROI release by tumour cells-stimulated monocytes was inhibited by anti-CD36 and anti-MR (clone PAM-1) mAbs., Conclusion: SR and MR may be involved to different extents in the induction of cytokines and ROI production by monocytes, but not MDM, stimulated with tumour cells.

Objective: This study addressed the role of the pattern recognition receptors (PRR), which recognize different molecular structures present on microorganisms, apoptotic, senescent and tumor cells, in the stimulation of human monocyte and monocyte-derived macrophages (MDM) for the production of intracellular cytokines., Materials and Methods: Monocytes and MDM were stimulated with different ligands of scavenger receptors (SR) and mannose receptor (MR). Production of intracellular cytokines: tumor necrosis factor alpha (TNF alpha), interleukin 10 and 12 (IL-10, IL-12) was determined by flow cytometry following staining with anti-cytokine monoclonal antibodies (mAbs)., Results: The ligands of SR type A: fucoidan, polyguanylic acid (polyG), chemically modified low density lipoproteins (LDL), ligands of SR-B: native and chemically modified LDL, and ligand of mannose receptor (MR)-mannan induced strong expression of intracellular TNF alpha and weaker IL-10 in monocytes, while phosphatidylserine (PdS) was without effect. IL-12 was stimulated only by fucoidan and polyG. The induction of cytokine m-RNA generally followed the pattern and the magnitude of intracellular cytokine production. In MDM, intracellular TNF alpha and IL-12 expression was induced by mannan, native and modified LDL, but not other ligands. Expression of IL-10 was less pronounced and occurred following stimulation with fucoidan, polyG and modified, but not native, LDL., Conclusions: These results suggest that some PRR ligands may be involved in activation of monocytes/MDM for the production of mainly proinflammatory cytokines (TNF alpha, IL-12) implicating their role in the response to microbial and tumor invasion.

The in vitro model of tumour infiltrating macrophages (TIM)-tumour interactions in which monocytes and monocyte-derived macrophages (MDM) are cultured with cancer cells was used to assess immunophenotypic changes of interacting cells. Following short cocultures, monocytes, MDM and tumour cells were sorted out by FACS and the expression of several determinants was evaluated. Monocytes showed the induction of CD44v6 and v7/8, and up-regulation of CD16 (Fc gamma RIII), CD54 (ICAM-1), CD68 (macrophage maturation marker) and CD86 (costimulatory molecule B7.2). The increased expression of CD11a (LFA-1) and CD58 (LFA-3) was noted on some cancer cells. Up-regulation of TNFRII and HLA-DR was observed on both types of cells. MDM shared similar changes. Contact of monocytes, but not of MDM, with tumour cells led to Fas-FasL-dependent apoptosis of both types of cells. This study suggests that the immunophenotype of monocytes/macrophages and cancer cells may be modified during their bidirectional interactions in the absence of other microenvironmental elements that are present in the tumour stroma.

Tuberculosis (TB) is still a major health problem, both as a single disease entity and as a cofactor in AIDS. The interaction between macrophage and Mycobacterium tuberculosis (MTB) is a critical step in the establishment of an early chronic infection. This study analyses the capacity of MTB to induce apoptosis in cells obtained by broncho-alveolar lavage (BAL) from patients with reactive pulmonary tuberculosis and from AIDS patients with disseminated pulmonary tuberculosis. Apoptosis was increased three-fold in BAL cells obtained from patients with pulmonary tuberculosis and even more markedly in alveolar macrophages of MTB-infected AIDS patients, compared with controls. Apoptosis was analysed and characterized by propidium iodide (PI) incorporation, terminal deoxy transferase (TDT)-mediated dUTP-biotin nick end labelling (TUNEL), and tissue transglutaminase (tTG) expression. The MTB-macrophage interaction was also investigated in vitro by infecting monocyte-derived macrophages (MDM) with MTB (virulent strain H37Rv). The induction of apoptosis by MTB required viable bacteria, was dose-dependent, and was restricted to H37Rv. Infection with either Mycobacterium avium complex (MAC) or HIV-1 and treatment with heat-killed MTB failed to induce apoptosis.

To investigate the biological activity of peritoneal macrophages, cells isolated from dialysate of 30 patients with end-stage kidney disease treated by intermittent peritoneal dialysis and from ascites of 6 patients with cardiac insufficiency (relative control group) were added to autologous, phytohemagglutinin (PHA)-stimulated lymphocyte cultures. Macrophages of dialyzed patients induced a dose-dependent increase in autologous lymphocyte proliferation, whereas macrophages obtained from control subjects exerted a suppressive effect on those cultures. The enhanced lymphocyte proliferation by macrophages from dialyzed patients was corroborated by the increased metabolic activity of macrophages as evaluated by the increased nitro blue tetrazolium (NBT) reduction test and increased functional expression of Fc receptors (FcR). The subpopulation of macrophages from patients with HLA-DR antigens as determined by HB55 monoclonal antibody, inhibited lymphoproliferation in vitro. We conclude that peritoneal macrophages from dialyzed patients represent a heterogenous population of cells with different phenotypic and functional characteristics.

Monoclonal and conventional cryptococcal-specific T suppressor factors (TsF) (also called TsFmp) depress phagocytosis by a subset of macrophages, while picryl- and oxazolone-specific TsF depress the passive transfer of contact sensitivity. This paper shows that these haptene-specific TsF also inhibit phagocytosis by a subset of macrophages and, using this assay, that the anti-haptene TsF resemble the anti-cryptococcal TsF in five respects: (i) the need for reexposure to specific antigen to trigger the release of TsF; (ii) genetic restriction in action; (iii) possession of an antigen-binding site; (iv) expression of I-J determinants; and (v) inactivation by reduction and alkylation. Purification of the anti-picryl TsF by sequential affinity chromatography indicates that the inhibition of phagocytosis is due to the TsF itself and not to a TsF-antigen complex. The TsF inhibits phagocytosis by a direct action as macrophages treated with TsF and exposed to antigen do not release a second factor which inhibits phagocytosis. These results and those of the accompanying paper indicate that the anti-cryptococcal and anti-haptene TsF are functionally equivalent, antigen-specific suppressor factors.

Monoclonal anti-cryptococcal TsF (which inhibits phagocytosis by macrophages) and anti-picryl TsF use the same two circuits to block the transfer of contact sensitivity (CS). Both arm macrophages which then release a macrophage suppressor factor (MSF) when exposed to antigen. This MSF depresses the transfer of CS. The evidence suggests that a single molecular species of TsF (MW ca. 70 kDa), which bears an antigen-binding site and I-J determinant, is responsible for MSF production and inhibition of phagocytosis. Anti-cryptococcal TsF also arms the T acceptor cell which then releases nsTsF-1 after triggering with a specific antigen (SCPA). This nsTsF-1, which depresses the transfer of contact sensitivity, was authentic, as shown by its I-J positivity (in contrast to MSF) and its role in the production of nsTsF-2. As anti-picryl TsF also inhibits phagocytosis, it was concluded that anti-cryptococcal TsF, originally detected by the inhibition of phagocytosis, and anti-picryl TsF, originally detected by inhibition of CS, are functionally equivalent.

Functional activity of peritoneal macrophages of 50 patients with end-stage renal failure on intermittent peritoneal dialysis (IPD) and of 30 control subjects with normal renal function was determined. Phagocytosis of latex particles by macrophages of dialyzed patients was significantly lower as compared with the controls. Further depression of the phagocytic activity was observed during bacterial peritonitis. Macrophages from the dialyzed patients also showed nonsignificantly decreased functional expression of Fc receptors (FcR) and increased spontaneous nitro blue tetrazolium (NBT) reduction.

Macrophages are essential for the proliferative response of human T lymphocytes to a purified polysaccharide extract from Candida albicans (MPPS). The role of macrophages as antigen-presenting cells in the production of an antigen non-specific inhibitory factor (nsINH) by MPPS-activated T cells was also investigated. Fc receptor positive (FcR+) or negative (FcR-) plastic-adherent mononuclear cells were used as MPPS-presenting cells, and the results show that the FcR- subset is mainly responsible for the release of nsINH from activated T cells.

We have examined the ability of macrophages (Mphi) to transmit T-cell derived suppressor signals to other T cells. The suppressor signal studied is an antigen-specific factor which suppresses the ability of adoptively transferred, sensitized lymphocytes to express contact hypersensitivity in normal recipients. We have found that this factor binds to peritoneal exudate Mphi via cell surface structures which can be blocked with heat-aggregated gamma globulin. Dead (HK) Mphi bind the factor but fail to present it in a functional way to assay (immune) T cells, whereas live (L) Mphi perform both functions. Further, L Mphi can retrieve the factor in an active form from the surfaces of HK Mphi. Based on these and other findings (1-5), we discuss the possibility that Mphi may play as important a role in presenting T-cell communication signals to the cells of the immune system as they do in presenting antigen.

The effect of the lymphocytes from picryl sulfonic acid treatment animals on primary and secondary humoral immune response to TNP hapten was investigated. These cells known to inhibit contract sensitivity reactions were also able to depress primary IgM response. When peritoneal exudate cells from normal mice incubated in suppressor supernatant were transferred into primed mice the suppression of IgM but no IgM secondary response was observed. In contrast peritoneal exudate cells incubated in control supernatant augmented IgM but didn't affect IgG response. It is postulated that normal peritoneal exudate cells (presumably macrophages) can stimulate IgM response. This enhancing activity could be partially blocked by soluble suppressor factor.

Lymphoid cells of mice injected with picrylsulphonic acid and then painted with picryl chloride produce a specific T suppressor factor (TSF) in vitro. This factor arms peritoneal exudate cells, which then produce a nonspecific factor which inhibits the transfer of contact sensitivity by immune cells incubated in it. An adherent, theta-negative cell, which is presumably a macrophage, is responsible. This justifies the use of the term macrophage suppressor factor. As a separate phenomenon, passive transfer cells lose their activity when incubated on high density monolayers of normal peritoneal exudate cells. However, this is not associated with the production of a supernatant factor. The inhibition of transfer when immune cells are incubated with specific TSF is unaffected by nylon wool filtration (which removes macrophages). This suggests that TSF is able to depress the passive transfer of contact sensitivity by a macrophage-independent process.

The respiration rate, aerobic glycolysis and glycolytic enzyme activities of purified mouse peritoneal macrophages increase during phagocytosis of either free or antibody-coated SRBC. These changes, however, seem to be roughly parallel to the amount of phagocytized antigen. In the digestive phase, Ag-Ab complexes induce more marked changes in macrophage metabolism than a comparable amount of free antigen. Lactate production, activity of several glycolytic enzymes and alanine-aminotransferase as well as glycogen content are greatly affected. Since in cell transfer experiments macrophage-associated SRBC can prime normal recipients for antibody response, whereas cell-associated SRBC-antibody complexes cannot, it is concluded that the changed macrophage metabolism drives antibody-coated antigen into metabolic channels allowing its rapid and total degradation.

Contact sensitivity skin reactions were produced in mice by immunization with 2-phenyl-4-ethoxymethylene oxazolone (oxazolone) and detected by the increase in ear thickness after challenging the ears with 2% oxazolone. These skin reactions can be transferred from immunized donors to irradiated recipients by peritoneal exudate cells induced by thioglycollate. The peritoneal exudate cells were separated into purified macrophage and purified lymphocyte populations. Both cell populations transferred skin reactions. However, their time course was different. The reactions produced by lymphocytes were greater at 24 hr than at 12 hr while the reactions produced by macrophages declined slightly between 12 and 24 hr. The working hypothesis was formed that the peritoneal lymphocytes conveyed a factor (presumptive cytophilic antibody) to peritoneal macrophages which enabled them to transfer ear reactions. Experiment showed that peritoneal and lymph node lymphocytes from sensitized donors within a Millipore chamber conveyed a factor to macrophages outside the chamber which enabled them to transfer ear reactions. In contrast, peritoneal macrophages (from sensitized donors) within the chamber and peritoneal lymphocytes outside the chamber were inactive. These findings suggested that there are three modes of immunological tissue damage: hypersensitivity mediated by lymphocytes (classical delayed hypersensitivity), hypersensitivity mediated by circulating antibody (classical immediate type hypersensitivity), and hypersensitivity mediated by macrophages which have passively acquired a factor (macrophage-mediated hypersensitivity).

The water soluble, chemically reactive thioglycollic acid thioether derivatives of oxazolone and picryl chloride were synthesized and tested for their ability to prevent the development of contact sensitivity. Mice given two injections of these agents showed partial or complete unresponsiveness when subsequently sensitized and challenged with oxazolone and picryl chloride, respectively. This unrespon siveness was associated with T suppressor cells, Ts-eff(cs), which blocked the efferent stage of the con- tact sensitivity reaction, i.e. the passive transfer of contact sensitivity. These Ts-eff (a) were entirely specific when tested with the corresponding antigen. However, the suppression which they caused had a non-specific final common pathway. Cells from mice injected with the oxazolone and picryl thioethers and painted with the corresponding contact sensitizer produced a suppressor factor in vitro. This factor specifically blocked passive transfer by immune cells incubated in it. It also armed macrophages which then caused suppression. These macrophages were most effective when injected intraperitoneally. The suppressor factor had a molecular weight between 30,000 and 100,000 and the α-oxazolone factor was absorbed by oxazolone-albumin Seph arose and could be eluted with oxazolone-∊-aminocaproic acid. It was also absorbed by concanavalin-A-sepharose and could be eluted with α-methylmannoside. It is proposed that the ability of water soluble, chemically reactive haptenes to evoke a Ts-eff(cs) population may be relevent to the rarity of severe drug reactions following the injection of chemically reactive drugs. [ABSTRACT FROM AUTHOR]

Macrophages are essential for the proliferative response of human T lymphocytes to a purified polysaccharide extract from Candida albicans (MPPS). The role of macrophages as antigen-presenting cells in the production of an antigen non-specific inhibitory factor (nsINH) by MPPS-activated I cells was also investigated. Fc receptor positive (FcR+) or negative (FcR+) plastic-adherent mononuclear cells were used as MPPS-presenting cells, and the results show that the FcR+ subset is mainly responsible for the release of nsINH from activated T cells. [ABSTRACT FROM AUTHOR]