Effects of bilirubin on murine peritoneal and spleen cells

The effect of bilirubin on murine peritoneal and spleen cells was investigated. Bilirubin was found to have a strong and rapid effect on the expression of various kinds of Fc receptors on peritoneal macrophages. Significant changes were observed 30 min after the infection of bilirubin. The return to normal values was not observed earlier than after 24 h. The effect of bilirubin on Fc receptor expression of splenic macrophages was less pronounced. Expression of Ia antigen on macrophages was not influenced by bilirubin. The changes in percentage of sIg+ and Thy 1.2+ lymphocytes reflect a change in the ratio of T to B cells in the peritoneal cavity, as bilirubin caused 40% increase in numbers of B cells and a similar decrease in numbers of T cells. The percentage of splenic B lymphocytes was not influenced by bilirubin injection; but the ratio of T helper to suppressor cells was altered.     

Use of mice tolerant to lipopolysaccharide to demonstrate requirement of cooperation between macrophages and lymphocytes to generate lipopolysaccharide-induced colony-stimulating factor in vivo

Injection of lipopolysaccharide (LPS) into mice was followed by a rapid elevation of colony-stimulating factor (CSF) in the serum. A second, challenging injection of LPS given 3 to 4 days later failed to induce elevated levels of CSF in the serum. Such mice tolerant to LPS were used as an experimental tool to identify the CSF-producing cells which respond to LPS. We observed that generation of LPS-induced CSF in mice tolerant to LPS could be restored by an intraperitoneal injection of spleen cells 24 h before the challenging injection of LPS. Depletion of the adherent cells from the spleen cells reduced the ability of the splenic lymphocytes to restore the capacity of the mice tolerant to LPS to generate serum CSF. Reconstitution of the splenic lymphocytes with 5% thioglycolate-elicited peritoneal macrophages, however, reestablished the restorative capacity of these cells, whereas almost no restoration was observed after direct injection of elicited peritoneal macrophages. These data suggest that the spleen cells are active in generating CSF, provided that macrophages are present and can interact with the splenic lymphocytes to generate LPS-induced CSF in the serum.     

No effect of recombinant human interleukin-1 on numbers of peripheral blood and peritoneal leukocytes during acute inflammation

Recombinant human interleukin-1 (IL-1) can prolong the survival of mice with severe systemic bacterial or fungal infections. In order to assess whether this is due to an effect of IL-1 on the production of leukocytes or their migration to the site of infection, the influence of IL-1 on the influx of leukocytes to the site of an acute inflammation was studied in normal and in granulocytopenic mice. The numbers of granulocytes, lymphocytes, and monocytes or macrophages in both the circulation and the peritoneal cavity were determined during an acute sterile inflammation elicited by intraperitoneal injection of either newborn calf serum (NBCS) or heat-killedCandida albicans, and during a peritoneal infection with viableC. albicans. After normal mice were injected intraperitoneally with NBCS or 10⁷ CFU heat-killed or viableC. albicans, the number of peritoneal granulocytes rose sharply within 6 h. Pretreatment of mice with a single intraperitoneal dose of 80 ng IL-1 24 h before injection of an inflammatory stimulus did not influence the course of the numbers of leukocytes in the circulation or in the peritoneal cavity. When mice were rendered granulocytopenic by cyclophosphamide, both the influx of granulocytes into the peritoneal cavity and the concomitant rise in the number of peripheral blood granulocytes after injection of NBCS, killed or viableC. albicans was virtually absent. Pretreatment of granulocytopenic mice with IL-1 did not influence the course of the numbers of leukocytes in either the circulation or the peritoneal cavity. These findings show that the beneficial effect of a single dose of IL-1 on the course of candidal infections in normal or granulocytopenic mice is not attributable to the influx of granulocytes or monocytes.     

The cellular cancer resistance of the SR/CR mouse

The SR/CR mouse phenotype, first described in 1999 in BALB/c and later bred into C57BL/6 mice, is resistant to cancer formation following high doses of cancer cells administered intraperitoneally. The tumor cell targeting and destruction mechanisms have not been identified. By fluorescence‐activated cell sorting analysis, the immune response of SR/CR mice after intraperitoneal injection of cancer cells was investigated and compared with parent strain mice. A massive influx of leukocytes into the peritoneal cavity was found. A large fraction of these leukocytes were polymorphonuclear granulocytes, macrophages and natural killer cells. A relative decrease in influx of B‐cells compared with controls was demonstrated. Increased proportions of leukocytes belonging to the innate immune system were also demonstrated in splenocytes of SR/CR mice. Cytospins of peritoneal fluid from SR/CR mice after cancer cell injection showed formations of immune cells morphologically resembling polymorphonuclear granulocytes and macrophages adjoining the cancer cells. The results point to the potential involvement of innate immune cells in cancer immunology. Our data support migration of polymorphonuclear granulocytes, macrophages and NK cells into the peritoneum of the SR/CR mouse in response to intraperitoneal injection of S180 cancer cells. The cell composition of spleens of SR/CR mice reflected the differential regulation of the innate immune cells in peritoneal exudates. Both peritoneal exudates and the spleens of SR/CR mice contained decreased proportions of B‐cells compared with BALB/c and C57BL/6 mice. We reproduce important aspects of previous published data and further extend them by showing differentially regulated populations of splenocytes including B‐lymphocytes in SR/CR mice compared with parent strain controls. Importantly, this differentially regulated immune response of SR/CR mice could not be found in response to challenge with the lymphoma cell line EL‐4.     

Studies on phytohemagglutinin-induced peritonitis of mice: dynamics of inflammatory responses and influence of anticomplementary agents and anti-inflammatory drugs

The intraperitoneal injection of phytohemagglutinin in the mouse resulted in the marked accumulation of leukocytes, especially macrophages, in the peritoneal cavity between 8 and 36 h after the injection. Parallel to the accumulation of macrophages, exudation of plasma proteins into the peritoneal cavity was observed. When the effect of anticomplementary agents (FUT-175 and K-76 COONa) and anti-inflammatory drugs (indomethacin and dexamethasone) on phytohemagglutinin-induced peritonitis was examined, FUT-175, K-76 COONa and indomethacin suppressed only the plasma protein exudation. On the other hand, dexamethasone suppressed both the accumulation of macrophages and the plasma protein exudation.     

Further comparisons of endogenous pyrogens and leukocytic endogenous mediators.

It was recently shown (Murphy et al., Infect. Immun. 34:177-183), that rabbit macrophages produce two biochemically and immunologically distinct endogenous pyrogens. One of these has or copurifies with substances having a molecular weight of 13,000 and a pI of 7.3. This protein was produced by blood monocytes or inflammatory cells elicited in 16-h rabbit peritoneal exudates. These acute peritoneal exudates were produced by the intraperitoneal injection of large volumes of saline containing shellfish glycogen. When the leukocytes in these exudates were washed and incubated at 37 degrees C in saline, they released an endogenous pyrogen. The injection of this pyrogen into rabbits, rats, or mice caused the biological manifestations which have been attributed to leukocytic endogenous mediator. These effects were increases in blood neutrophils, the lowering of plasma iron and zinc levels, and the increased synthesis of the acute-phase proteins. The other rabbit endogenous pyrogen seems to be a family of proteins with isoelectric points between 4.5 and 5.0. These proteins are produced by macrophages in the lung, liver, or in chronic peritoneal exudates. In these experiments, the lower-isoelectric-point endogenous pyrogens were produced by macrophages from the peritoneal cavity of rabbits that had been injected 4 days earlier with 50 ml of light mineral oil. These rabbit pyrogens were found to have leukocytic endogenous mediator activity in mice but to be completely inactive in rats. When injected into rabbits, these proteins produced fever, lowered plasma iron, increased blood neutrophils, but failed to elevate plasma fibrinogen.     

Differential Effects of Escherichia coli Subtilase Cytotoxin and Shiga Toxin 2 on Chemokine and Proinflammatory Cytokine Expression in Human Macrophage,Colonic Epithelial,and Brain Microvascular Endothelial Cell Lines

Subtilase cytotoxin (SubAB) is the prototype of a recently emerged family of AB5 cytotoxins produced by Shiga-toxigenic Escherichia coli (STEC). Its mechanism of action involves highly specific A-subunit-mediated proteolytic cleavage of the essential endoplasmic reticulum (ER) chaperone BiP. Our previous in vivo studies showed that intraperitoneal injection of purified SubAB causes a major redistribution of leukocytes and elevated leukocyte apoptosis in mice, as well as profound splenic atrophy. In the current study, we investigated selected chemokine and proinflammatory cytokine responses to treatment with SubAB, a nontoxic derivative (SubA_A272B), or Shiga toxin 2 (Stx2) in human macrophage (U937), brain microvascular endothelial (HBMEC), and colonic epithelial (HCT-8) cell lines, at the levels of secreted protein, cell-associated protein, and gene expression. Stx2 treatment upregulated expression of chemokines and cytokines at both the protein and mRNA levels. In contrast, SubAB induced significant decreases in secreted interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) in all three tested cell lines and a significant decrease in secreted IL-6 in HBMECs. The downregulation of secreted chemokines or cytokines was not observed in SubA_A272B-treated cells, indicating a requirement for BiP cleavage. The downregulation of secreted chemokines and cytokines by SubAB was not reflected at the mRNA and cell-associated protein levels, suggesting a SubAB-induced export defect.     

Marked reduction of mouse peritoneal CD5+ B cells by intraperitoneal administration of lipopolysaccharide.

Intraperitoneal administration of lipopolysaccharide to mice induced a marked reduction of CD5+ B cells in the peritoneal cavity. The reduction was not induced by intravenous, subcutaneous, or oral administration of lipopolysaccharide. The reduction continued for about 10 days after the injection, and the CD5+ B-cell count recovered to the normal state about 14 days after the injection. The reduction of peritoneal CD5+ B cells might be caused by apoptotic cell death. Injection of lipopolysaccharide did not result in production of antibody to lipopolysaccharide. On the other hand, intraperitoneal injection of heat-killed bacteria did not induce a reduction of peritoneal CD5+ B cells and elicited the definite production of antibody to lipopolysaccharide.     

Splenic B cells function as immunogenic antigen-presenting cells for the induction of effector T cells

Previous studies performed in our laboratory have revealed that an ordered, sequential, tricellular interaction is obligatory for the antigen-driven induction of a specific effector memory T cell. Thus, it was found that antigen-pulsed peritoneal macrophages signal, in spleen cells, the generation of antigen-specific initiator lymphocytes. These lymphocytes, following injection to syngeneic recipients, recruit, in the draining lymph nodes, "virgin" antigen-reactive T lymphocytes. Although the nature of the first and last cell in the interacting sequence was well characterized, the identity of the intermediary initiator splenic cell was obscure. Studies were carried out to characterize the nature of the splenic initiator cells. It was found that spleen cells from nu/nu, adult thymectomized and neonatal thymectomized, or spleen cells from normal donors which had been subjected to cytolysis using anti-Thy-1.2 antibodies in the presence of complement, did generate, following interaction with keyhole limpet hemocyanin (KLH)-fed macrophages, specific initiator cells. Carrageenan impairment of spleen macrophages did not affect the generation of initiator cells, nor did the depletion of dendritic cells from the spleen. On the other hand highly enriched B cell, but not highly enriched T cell populations, when seeded on KLH-pulsed macrophages, generated antigen-specific initiators, which, in vivo, recruited antigen-reactive T cells. It thus appeared that B lymphocytes can function as intermediary obligatory antigen-presenting cells and actively transfer immunogenic signals from peritoneal antigen-presenting cells to T lymphocytes. These findings may therefore suggest that antigen-specific B cells do not function solely as antibody-producing cells, but, once activated by macrophages, may control the induction and differentiation of some antigen-reactive T cell subsets. Thus, one can view the B cell as an important regulatory cell of both cellular and humoral immune functions. The significance of this observation with regard to Ir gene control at the level of B lymphocytes is discussed.     

Characteristics of cells present in peritoneal fluids of mice injected intraperitoneally with Bordetella pertussis.

Peritoneal fluids obtained from mice after the intraperitoneal administration of Bordetella pertussis vaccine, heated vaccine, an extract of the organisms, killed Escherichia coli, or thioglycolate medium were examined in terms of total cells and percentage that adhered to glass cover slips during 2-h incubation period. All these substances were found to increase the number of leukocytes in peritoneal fluid within 1 to 2 days after the injection. This increase appeared to be due to an influx of macrophages and polymorphonuclear leukocytes with relative proportions at a given time dependent upon the material involved in the induction of the response. The initial increases after pertussis vaccine seemed to be due mainly to an influx of monomuclear cells, whereas with E. coli neutrophils constituted the major portion of the cell population. The percentage of peritoneal cells that attached to glass was also found to be markedly reduced in preparations obtained from mice after the injection of B. pertussis or E. coli. There appeared to be differences in persistence of this phenomenon, with preparations containing the histamine-sensitizing factor being the most active in affecting adherence properties. Thus these data would suggest that the action of B. pertussis on macrophages (or precursors) and neutrophils is not expressed in terms of suppression of emigration properties, as has been reported by others for lymphocytes, but is manifested in the alteration of glass-adherence characteristics. Within experimental limitations, it is believed that macrophages are possibly more involved in terms of altered function than are the polymorphonuclear cells.     

Accumulation of Immature B and Null Lymphocytes in the Periphery After Intraperitoneal Administration of Traditional Chinese Medicine, Xiao-Chai-Hu-Tang (Japanese Name : Shosaiko-to)

Accumulation of lymphocytes after an intraperitoneal (ip) injection of a traditional Chinese herb medicine, XIAO-CHAI-HU-TANG (Japanese name : shosaiko-to), was investigated. Shosaiko-to induced marked accumulation of lymphocytes rather than macrophages in the peritoneal cavity of ICR mice, whereas various kinds of irritants, e.g. proteose-pepton, Escherichia coli lipopoly-saccharide (LPS), OK-432 and Corynebacterium parvum, induced preferential accumulation of macrophages rather than lymphocytes. By means of analysis using two-color fluorescence-activated cell sorter (FACS), it was revealed that the increased lymphocyte subpopulations not only in the peritoneal cavity but also in the spleen of C3H/He mice by the injettion of shosaiko-to were comprised of both immature B(IgM⁺ and IgD^-) and null (thyl^- and Ig^-) cells. This effect of shosaiko-to was observed in other C5 normal strains, C3H/HeJ (LPS-nonresponder), C57BL/6, BALB/c and athymic nu/nu (ICR background) mice, but not in C5 deficient strains, AKR/J, A/J and DBA/2 mice, indicating that the accumulation of immature B and null cells in the periphery induced by shosaiko-to is closely related to the complement system.     

Cellular reactions in a SRBC-induced inflammatory exudate

Acute inflammatory exudates which are induced by the intra-peritoneal injection of sheep red blood cells contain a variety of connective tissue cell types. Granulocytes, macrophages and lymphocytes constitute the vast majority of the exudate cells. The peritoneal macrophages are principally involved in the phagocytosis and clearance of the whole SRBC from the peritoneal cavity. The exudate lymphocytes which accumulate during the first 24 hours are derived from a pool with a fast turnover rate and are newly formed. While these lymphocytes undergo an enlargement and increase their basophilic cytoplasm during this response, they fail to show increases in their DNA synthesis while in the inflammatory exudate.     

Polyclonal immunoglobulin synthesis induced by a macrophage factor acting via T cells.

New Zealand White rabbits were killed 7 days after immunization with 1 mg of alum precipitated, keyhole limpet hemocyanin (KLH) into each hind footpad and 3 days after intraperitoneal injection of thioglycollate. When supernatants from cultures of purified, elicited macrophages were added to Mishell-Dutton cultures of primed popliteal lymphocytes, they induced synthesis of both general immunoglobulins and antibody specific for KLH. The active factor(s), polyclonal lymphocyte activator (PLA), appears to be a glycoprotein with a molecular weight between 150,000 and 200,000 daltons. Absorption with high concentrations of thymocytes but not bone marrow cells removed polyclonal stimulatory activity from peritoneal macrophage supernatants which contained PLA. Purified lymph-node B cells were stimulated by PLA only in the presence of T cells. In addition, supernatants from PLA activated, washed T cells were effective at inducing polyclonal B-cell activation. Thus, PLA appears to act indirectly on B cells by stimulating T cells to produce a soluble factor which induces polyclonal B-cell activation.     

Inhibition of the accumulation of macrophages and the generation of macrophage chemotactic activity by dexamethasone in concanavalin A-induced peritonitis of mice

A delayed-type inflammatory response was evoked in mice using concanavalin A (Con A) as a stimulus, and the effect of various anti-inflammatory agents on the inflammations was examined. The intraperitoneal injection of Con A in the mouse resulted in the marked accumulation of leukocytes, especially macrophages, in the peritoneal cavity between 16 and 48 hr after the injection. Prior to the accumulation of macrophages, the chemotactic activity for macrophages appeared in the peritoneal fluid, and was associated with protein(s) in the molecular weight range from 10000 to 100000 daltons. When the effect of various agents on Con A-induced peritonitis was examined, neither anticomplementary agents (FUT-175 and K-76 COONa), bromophenacyl bromide, nordihydroguaiaretic acid nor indomethacin affected the generation of chemotactic activity and the accumulation of macrophages, suggesting that C5a, prostaglandins and leukotriene B₄ are hardly involved in the Con A-induced macrophage accumulation. On the other hand, dexamethasone suppressed both the generation of chemotactic activity and the accumulation of macrophages. Taking into consideration the observation that the synthesis of macrophage chemotactic factors by mitogen-stimulated lymphocytes is inhibited by glucocorticoids these results suggest that the macrophage chemotactic lymphokines might be involved in the accumulation of macrophages in Con A-induced peritonitis.     

Peritoneal B cells govern the outcome of diabetes in non-obese diabetic mice

Type 1 diabetes mellitus (T1DM) results from autoimmune destruction of insulin-producing beta cells in the pancreatic islets. Although T1DM is mediated by T lymphocytes, B lymphocytes are essential for insulitis and disease progression in the non-obese diabetic mouse model. We find that B cells invading the pancreas phenotypically resemble B1a B cells in the peritoneal cavity, including the presence of CD5+. To investigate the link between the peritoneal cavity and lymphocytes invading the pancreas, we used intraperitoneal hypotonic lysis to target these cells. B1a cells were eliminated from the peritoneal compartment by this treatment and were quickly replaced by B2 cells. Both B1a and B2 B cells were concordantly redistributed away from insulitis lesions, while pancreatic T cells showed little change. As a consequence of these events, the onset of diabetes was significantly delayed. These findings indicate that simple perturbations of the B cell-enriched peritoneal compartment can affect the disease process in the pancreas even after islet invasion has begun.     

Effects of glucocorticoid and antiglucocorticoid hormones on leukocyte numbers and function

Hormones were administered to mice in seven daily intraperitoneal injections of saline suspensions. Progesterone and cortexolone, which often fail to act as antiglucocorticoids in vivo, were found to have antiglucocorticoid effects on the immune system under these conditions. The effects seen were increases in numbers of lymphocytes, monocytes, neutrophils and total leukocytes in the blood, increases in the number of peritoneal exudate cells and splenic plaque-forming cells, and increased splenocyte responses to the mitogen phytohemagglutinin. Deoxycorticosterone, sometimes also considered to be an antiglucocorticoid, acted only as a glucocorticoid here. Both deoxycorticosterone and the glucocorticoid corticosterone had effects opposite to those produced by progesterone and cortexolone on these parameters.     

Adoptive transfer of protection against Trypanosoma cruzi with lymphocytes and macrophages.

Female C57BL/6J mice were infected with Trypanosoma cruzi and subsequently given macrophages or lymphocytes from syngeneic donors which had recovered from the acute infection. Mice which received immune peritoneal macrophages, splenic lymphocytes, or lymph node lymphocytes developed lower mean parasitemias and cumulative mortalities than did recipients of nonimmune cells. Neither peritoneal lymphocytes nor splenic macrophages were protective, however. These studies indicate that splenic and lymph node lymphocytes are effective in transferring protection against T. cruzi, whereas the macrophage is somewhat less effective.     

Immunocytochemical analysis of cellular responses to BCG.

The study reported here was performed to find out whether changes in the number of mycobacteria in various organs of BCG-infected mice can be related to changes in the phenotype of monocytes, macrophages and lymphocytes in the blood, various tissues, and peritoneal cavity and to the formation of granulomas in the spleen, liver and lungs. The relative amounts of various antigens on the leukocytes were assessed semi-quantitatively after immunocytochemical detection of the binding of monoclonal antibodies. Granuloma formation was determined after immunocytochemical staining of cells in sections of liver and lung tissue with a monoclonal antibody against the common leukocyte antigen and in sections of the spleen with a monoclonal antibody against the Mac-2 antigen. The results showed that during the first week of infection the number of BCG in spleen, liver and lungs declined considerably. Multiplication of mycobacteria during the second week of infection was associated with decreased expression of antigen F4/80 and increased expression of Ia antigen and Mac-2 antigen by blood monocytes and macrophages. Reduction of the numbers of BCG in the spleen and liver during the third week after i.v. injection of BCG and in lungs during the fourth week of the infection was found to be correlated with the degree of granuloma formation in these organs. After intravenous injection of killed BCG no changes were observed in the phenotype of monocytes and the macrophages in spleen, liver, lungs and peritoneal cavity. These mice showed considerably less granuloma formation than BCG-infected mice. The present results indicate that live but not killed mycobacteria induce macrophage activation.     

B cell apoptosis accelerates the onset of murine lupus

To investigate whether the increased rate of lymphocyte apoptosis in systemic lupus erythematosus is involved in the onset of the disease, apoptotic or necrotic T or B lymphocytes from various cell lines were injected intraperitoneally into pre-autoimmune (NZBxNZW)F1 mice (BW) and non-autoimmune BALB/c mice. The intraperitoneal production of cytokines and chemokines, the specific T cell response in the spleen, and the production of anti-histone and anti-dsDNA Ab were investigated. The onset of the disease was characterized by creatinine levels and evaluation of glomerular IgG deposits. In BW, but not in BALB/c mice, injection of apoptotic and not necrotic cells up-regulated IL-6 and IL-10 in resident macrophages. Administration of apoptotic cells augmented the number of Th2 and B lymphocytes recruited in the peritoneal cavity. Only the treatment with apoptotic B cells promoted a systemic Th2 autoimmune response to H2 histones, associated with earlier occurrence of high levels of anti-dsDNA autoantibodies, higher creatinine levels and more numerous glomerular IgG deposits than in BW controls not injected with apoptotic B cells. In genetically susceptible mice exposure to apoptotic of B, but not T, lymphocytes can elicit a Th2 response to H2 histones that helps B cell production of anti-dsDNA Ab and finally triggers the onset of lupus.     

Effect of virus infection on the inflammatory response. Depression of macrophage accumulation in influenza-infected mice.

To better define the mechanisms by which viruses depress immune function, the effect of influenza infection on the ability of macrophages to accumulate at sites of inflammation was determined. Mice were inoculated with virus, and their inflammatory response measured in vivo by counting the number of leukocytes which accumulated in the peritoneal cavity 2 days after an intraperitoneal injection of phytohemagglutinin. Mice infected with influenza had a 57% and 65% depression of total leukocyte and macrophage accumulation, respectively, as compared to the response of uninfected mice. In contrast, bacterial pneumonia did not produce a decrease in the macrophage response. This indicated that the depression was produced by the virus infection rather than being a nonspecific phenomenon accompanying any inflammatory focus in the lung. The in vitro chemotactic responsiveness of normal peritoneal macrophages incubated with infectious influenza virus was 53% of normal. These experiments suggest that influenza infection may depress a host's ability to mobilize macrophages to inflammatory sites in vivo by inhibiting their chemotactic responsiveness.