Effect of immunological stimulation on the production of platelet-activating factor by rat peritoneal cells: its relevance to anaphylactic reactions

The production of platelet-activating factor (PAF) by rat peritoneal cells was studied using as stimuli either monoclonal IgE, IgG1 or IgG2b anti-DNP (2,4-dinitrophenyl), and DNP-BSA. Peritoneal cells sensitized in vitro with any of these antibodies at concentrations higher than 10 nM and challenged with 1 microM DNP-BSA produced PAF. PAF production was also elicited by preformed IgE/ and IgG2b/DNP-BSA immune complexes, preferentially at a large antigen/antibody ratio. The production of PAF was unrelated to the activation of mast cells, since it occurred in populations depleted of mast cells by adherence to plastic dishes. Moreover, the release of [3H]serotonin from IgE-sensitized mast cells showed a time-course more rapid than PAF production and occurred in cells sensitized with IgE at concentrations lower than those required for PAF formation. In contrast, peritoneal cells sensitized with IgG1 and IgG2b failed to release [3H]serotonin. Rat peritoneal cells showed a significant ability to catabolize PAF by intracellular PAF-acetylhydrolase in view of both the amounts of enzyme activity assayed in cellular homogenates, and the 15-fold increase on controls of PAF quantities detected in peritoneal cells treated with phenylmethylsulfonyl fluoride (PMSF), a known inhibitor of PAF-acetylhydrolase. The PAF activity produced upon PMSF addition showed a retention time on reverse-phase HPLC which suggests structural identity to PAF produced by either immunological challenge or ionophore A23187. These data suggest that PAF formed during rat passive anaphylaxis reactions depends on the activation of mononuclear phagocytes. This production may be triggered by two types of low affinity receptors: Fc epsilon RII/CD23 and Fc gamma R. The ability of peritoneal cells to catabolize PAF by intracellular acetylhydrolase seems unaffected by immunological stimulation.

Contribution of N-acetyl-beta-D-galactosamine-specific lectin to Fc receptor-mediated phagocytosis by mouse peritoneal macrophages

The contribution of lectin-like receptors on the cell surface of mouse peritoneal macrophages to the process of phagocytosis of IgG-coated sheep red blood cells (SRBC) through Fc receptors has been investigated. Phagocytosis was activated by conditioned medium containing modified vitamin D3-binding protein (DBP) prepared by the incubation of foetal calf serum (FCS) with lysophosphatidyl-choline-treated splenic non-adherent cells. Fc receptor-mediated phagocytosis of opsonized SRBC was specifically inhibited by the addition of N-acetyl-beta-D-galactosamine. The binding of modified Gc globulin, human DBP, to peritoneal macrophage was only inhibited by the addition of N-acetyl-beta-D-galactosamine, and was dependent on N-acetyl-beta-D-galactosamine concentration. In the presence of cycloheximide, activated phagocytosis was reduced to control levels. By Scatchard plot analysis of binding studies, the number of Fc receptors of macrophages which were activated by conditioned medium increased 3.6-fold in comparison to that of control macrophages. These findings suggest that lectin-like receptors having a specificity to N-acetyl-beta-D-galactosamine are involved in activating the process of Fc receptor-mediated phagocytosis of opsonized SRBC by macrophages, and that modified DBP promotes the synthesis of Fc receptors through the N-acetyl-beta-D-galactosamine-specific lectin on macrophage surface.

Activity of human peritoneal macrophages against a human tumor: role of tumor necrosis factor-alpha, PGE2 and nitrite, in vitro studies

Human peritoneal macrophages collected from renal patients on continuous ambulatory peritoneal dialysis (CAPD) during inflammation-free periods were induced to express antitumor activity in vitro when cultured in the presence of bacterial lipopolysaccharide (LPS) and even more activity when they were kept in the presence of LPS + IND (indomethacin). The antitumor activity was expressed against a human tumor-cell line, RC43, either in a cell-to-cell contact set-up between the macrophages and the RC43 target cells or when the tumor cells were exposed to supernatants of the cultured macrophages. The antitumor activity of macrophages was correlated to a marked increase in production of tumor necrosis factor-alpha (TNF alpha), not correlated to an increase in nitrite production and inversely correlated to the production of PGE2. The RC43 tumor cells were susceptible to recombinant human TNF alpha, recombinant human IL-1 beta, sodium nitrite and the leukotriene LTB4. The results obtained suggest that activated human macrophages might represent a useful tool for cancer immunotherapy.

Organ-association phenomena during sepsis. TNF and IL-6 in different macrophages

Sepsis was induced in rats by cecal ligation and perforation (CLP). Five and 15 hours post CLP, alveolar macrophage (AM), Kupffer cell (KC), and peritoneal macrophage (PM) were isolated and cultured for 18 hours. Culture supernatant was examined for bioactivity of tumor necrosis factor (TNF) and interleukin 6 (IL-6) and response to lipoplysaccharide (LPS) stimulation in vitro. Results showed that AM produced more TNF during sepsis as compared with KC and PM. Stimulation with LPS in vitro was responded only by AM at 15 hr after CLP. Pattern of IL-6 production was different from TNF while KC produced the highest level of IL-6 after induction of sepsis.

[The characteristics of the biological properties of capsule-free variants of Francisella tularensis]

Comparative study of the properties of initial capsular (cap+) and non-capsular (cap-) F. tularensis strains has revealed that the non-capsular variants have their specific biological features. The characteristic features of these variants are avirulence and inability to produce an immunogenic effect in sensitive laboratory animals. Cap- mutants, depending on the method of their obtaining, may exhibit different sensitivity to some antibacterial preparations. In contrast to the initial virulent strains, cap- variants are intensively phagocytosed by peritoneal macrophages of white mice and capable of multiplication and survival in these macrophages. F. tularensis non-capsular forms are characterized by higher superoxide-dismutase and neuraminidase activity than the initial strains, which may be the explanation of the phenomenon of their intracellular survival. At the same time the main biochemical signs of cap- strains (citrullinureidase, phosphatase and penicillinidase) remain unchanged, which determines the possibility of their classification with this subspecies.

[Experimental analysis of cytotoxicity mediated by activated macrophages against glioma cells in mice]

Macrophage (M phi) has a very important role in host natural defence and tumor cell killing. Activated M phi with tumor cytotoxicity can be induced by various lymphokines, such as interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, IL-4, granulocyte macrophage-colony stimulating factor (GM-CSF), and macrophage-colony stimulating factor (M-CSF), but also by various bacterial products, such as lipopolysaccharide (LPS), Bacillus Calmette Guérin (BCG), corynebacterium parvum (C.p.), and muramyl-dipeptide (MDP). Although the brain is considered as an "immunologically privileged site", it has been demonstrated that in malignant brain tumors infiltration of lymphocytes or M phi can be seen in tissue samples. This may suggest that immune surveillance exists in the brain. But the biological significance of infiltrative M phi is unclear. The purpose of this study is to confirm the significant generation of activated M phi with cytotoxicity to glial tumor cells and to elucidate the cytotoxic mechanism associated with cellular interaction between effector M phi and target cells. This is the first report on experimental analysis of cytotoxicity mediated by activated M phi against glioma cells in mice. The cytotoxicity mediated by murine peritoneal activated M phi was examined against 3 kinds of murine glioma cell lines; VM-Glioma (spontaneously occurring astrocytoma of the VM mouse origin, H-2b), RSV-M (Schmitt-Ruppin Rous sarcoma virus-induced malignant glioma of the C3H/He mouse origin, H-2k), and 203-Glioma (methylcholanthrene-induced ependymoblastoma of the C57BL/6 mouse origin, H-2b). Activated M phi were obtained from peritoneal exudate cells of 4 strains of mice, C57BL/6 (H-2b), C3H/He (H-2k), DBA/2 (H-2d), and BALB/c (H-2d), following intraperitoneal injection of (1) LPS 200 micrograms, (2) BCG 200 micrograms, (3) C.p. 200 micrograms, (4) MDP 350 micrograms, and (5) IFN-gamma 10(3) units, 7 days prior to 20 hr 51Cr release-cytotoxicity assay. Of the various combination of mouse strains and activating agents tested, that of activated M phi of the C3H/He mouse with induction by LPS had the most tumoricidal effect against the glioma cells, which was not MHC restricted. Although LPS-activated M phi underwent marked loss of cytotoxicity within 24 hr following initiation of in vitro culture, this 20 hr pretreatment with IFN-gamma or TNF-alpha inhibited this reduction in tumoricidal effects in a dose dependent fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

Apyrogenic synthetic desmuramyldipeptide, LK-409, with immunomodulatory properties

The synthesis and some immunological characteristics of a new desmuramyl dipeptide 7-oxooctanoyl-L-alanyl-D-isoglutamine (LK-409) are presented. The effects of this compound were compared with those of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP). The influence of LK-409 on the number of B and T cells in spleen and the number of peritoneal macrophages was studied; Jerne's plaque forming cells assay was performed to monitor the effect of B cell differentiation. The blast transformation of T cells stimulated with concanavalin A was used to detect the influences on T lymphocytes. The activation of macrophages was studied as well. In contrast to MDP, LK-409 was apyrogenic in the doses applied but had similar immunomodulatory properties. Tested immunological properties and the absence of pyrogenicity and low toxicity make LK-409 a candidate for an immunomodulatory drug and a model molecule suitable for studying and understanding the dual activity of the MDP and its analogues.

[The effect of a vaccinal strain of Yersinia pestis on lysosome fusion with phagosomes in peritoneal and alveolar macrophages]

It is established that the frequency of phagosome-lysosome fusion in alveolar macrophages is lower than in the peritoneal cells upon endocytosis of Yersinia pestis. The subcutaneous immunization activates the phagosome-lysosome fusion in peritoneal macrophages, whereas alveolar cells remain without change. The aerogenic vaccination stimulates this process in both peritoneal and alveolar macrophages, as distinct from subcutaneous immunization.

Effect of gangliosides in the autoimmune response induced by liposome-associated antigens

A model of autoimmunity to rat male accessory glands (RAG) was recently developed by intraperitoneal administration of three doses of native RAG associated with liposomes. In this work we analysed the effects of gangliosides in the cellular response to RAG when they were intraperitoneally administrated prior to the second dose of liposome-associated RAG. Results show that the ganglioside treatment could modify an established DTH response. Also, gangliosides markedly reduced the number of Ia antigen-positive peritoneal exudated cells (PEC). However, they modified neither the processing of liposomes through PEC nor their viability. Moreover, we obtained cellular response by transferring PEC from immunized donors into naive receptors.

Alpha-D-galactosylation of surface fucoglycoconjugate(s) upon stimulation/activation of murine peritoneal macrophages

Murine resident macrophages express, on their surface, carbohydrate epitopes which undergo changes during their stimulation/activation as monitored by binding of 125I labelled Evonymus europaea and Griffonia simplicifolia I-B4 lectins. Treatment of the stimulated macrophages with coffee bean alpha-galactosidase abolished binding of the GS I-B4 isolectin and changed the binding pattern of the Evonymus lectin. The affinity (Ka) of Evonymus lectin for alpha-galactosidase-treated macrophages decreased approximately 23-fold, from 1.25 x 10(8) M-1 to 5.5 x 10(6) M-1. Subsequent digestion of alpha-galactosidase-treated macrophages with alpha-L-fucosidase from Trichomonas foetus, further reduced binding of Evonymus lectin. Resident macrophages showed the same pattern of Evonymus lectin binding, with the same affinity, as alpha-galactosidase-treated, stimulated macrophages. These results, together with a consideration of the carbohydrate binding specificity of the Evonymus lectin which, in the absence of alpha-D-galactosyl groups, requires alpha-L-fucosyl groups for binding, indicate the presence, on resident macrophages, of glycoconjugates with terminal alpha-L-fucosyl residues. It is also concluded that during macrophage stimulation/activation alpha-D-galactosyl residues are added to this glycoconjugate and that they form part of the receptor for Evonymus lectin. The same glycoconjugate(s) is/are also expressed on the activated macrophage IC-21 cell line which exhibits the same characteristics as that of stimulated peritoneal macrophages, i.e., it contains alpha-D-galactosyl end groups and is resistant to the action of trypsin. Both lectins were also specifically bound to Corynaebacterium parvum activated macrophages.

In vivo effects of OK-432, inosine pranobex and its salt components on macrophage subpopulations in spleen and peritoneum of mice during the primary humoral immune response

Subsets of macrophages (BM 8-, la- and esterase-positive subtypes) in the spleen and the peritoneum of mice were affected differently by immunomodulators during the humoral immune response. I.p. application of inosine pranobex (INPX), as well as of its salt moiety (DIPPACBA) and its dimethylaminopropanol (DIP) and acetamidobenzoic acid (PACBA) components, increased the number of nonspecific esterase-bearing cells in the peritoneum on day 3. INPX and DIPPACBA stimulated the la+ macrophage on day 3, DIPPACBA the BM 8+ macrophage only on day 1 and DIP on day 5. In spleen, DIP and PACBA had marked effects on the la+ subset in addition to a marginal effect on the BM 8+ phenotype on day 1. DIPPACBA also influenced the BM 8+ macrophage slightly on day 1. In contrast, the microbial product OK-432 stimulated BM 8+ and la+ macrophages in spleen markedly on day 1, but only marginally on days 3 and 5. However, it exerted a strong effect on both subtypes in peritoneum on days 3 and 5. OK-432 was found to be without any influence on esterase-bearing macrophages. The results show that the heterogeneity of macrophages is not only represented by subset markers, but also by their susceptibility to immunomodulators in different organs and stages of the immune response.

Impairment of antibacterial defense mechanisms of the lung by extrapulmonary infection

To determine whether extrapulmonary infection alters antibacterial defenses of the lung, we challenged mice with peritonitis due to Escherichia coli by aerosol inhalation with either Staphylococus aureus or Pseudomonas aeruginosa. In animals without peritonitis, 14% +/- 5% and 11% +/- 1% of the initially deposited viable S. aureus and P. aeruginosa, respectively, remained in the lungs at 4 hr. In contrast, in mice with peritonitis, at 4 hr 45% +/- 9% of the staphylococci were recoved, and the P. aeruginosa had increased to 948% +/- 354% of the initial inoculum. Proliferation of P. aeruginosa in mice with peritonitis was associated with impaired recruitment of polymorphonuclear neutrophils (PMNs) into the lungs. In contrast, a noninfectious stimulus induced more PMNs into the peritoneal cavity than did intraabdominal sepsis but only minimally impaired PMN recruitment into the lungs after aerosol challenge with P. aeruginosa. Sterile intraperitoneal stimulation did not significantly impair intrapulmonary killing of P. aeruginosa. Levels of antigenic C3 and functionally active C5 were significantly depleted in mice with peritonitis due to E. coli. We conclude that the systemic effects of sepsis, including complement depletion, contribute to the decreased pulmonary PMN recruitment and to impaired intrapulmonary bacterial killing of animals with peritonitis due to E. coli.

Induction of acquired cellular resistance in mice with viable and macrophage-processed Listeria monocytogenes

Intracutaneous immunization of mice with 10(5) or 10(6) viable listeria resulted in acquired cellular resistance (ACR) of short duration (7 days). The period during which viable Listeria monocytogenes had to be present in order to induce ACR was estimated by killing the listeria at different times after immunization by injecting the bactericidal antibiotic amoxycillin. The killing of listeria within 6 h after injection prevented the induction of A CR completely, between 6 and 12 h partially, while survival of listeria within animals for at least 18 h was required for the induction of complete protection. To determine whether multiplication of viable listeria was a prerequisite for the induction of ACR, the bacteriostatic antibiotic minocycline was injected for four days after immunization. Induction of ACR was only possible if the dose of viable listeria was large enough to permit a proportion of the listeria to escape bacteriostasis. Interaction of peritoneal macrophages of normal mice and viable listeria yielded a supernatant which induced specific ACR in normal recipient mice. No ACR could be induced with supernatant obtained from normal macrophages after digestion of killed listeria. A reduced level of ACR was obtained with supernatant collected after interaction of macrophages from immune mice and viable listeria. The immunogenic material present in the supernatant of normal macrophages after interaction with viable listeria is thermolabile, has a molecular weight of over 300,000, and is not affected by treatment with DNase, RNase, or trypsin.