Modulation of myelopoiesis by different bacterial cell-wall components: induction of colony-stimulating activity (by pure preparations, low-molecular-weight degradation products, and a synthetic low-molecular analog of bacterial cell-wall components) in vitro

Investigation of acute-phase proteins and cytokines response in goats with contagious caprine pleuropneumonia with special reference to their diagnostic accuracy

Acute-phase proteins (APPs) have always had valued diagnostic potentialities in response to infection. This study aimed to evaluate the diagnostic accuracy of selected APPs and proinflammatory cytokines (PIC) in goats with contagious caprine pleuropneumonia (CCPP) under field conditions. Moreover, to highlight the role of tested biomarkers in CCPP pathogenesis. Fifty-eight goats (38 confirmed cases with CCPP and 20 healthy controls) were involved in this investigation. C-reactive protein (CRP), procalcitonin (PCT), haptoglobin (HP), fibrinogen (Fb), serum amyloid A (SAA), selected PIC (IL1-α, IL1-β, IL-6, interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α)) levels were investigated in serum samples from all goats under investigation. Latex agglutination test was used for diagnosis of goats with CCPP. For microbiological investigations, nasopharyngeal swabs (from all goats), lung tissues and pleural fluids (from only necropsied goats) were collected. This study revealed that all tested parameters have a high to moderate degree of diagnostic performance for CCPP. Magnitudes of increase in levels of APPs (CRP, HP and SAA) were stronger than PIC, IFN-γ, Fb and PCT. All tested parameters showed high diagnostic accuracy (AUROC >90%), except HP (AUROC = 87.3%) and IFN-γ (AUROC = 78.8%) showed moderate accuracy in differentiation of goats with and without CCPP infection. For detecting goats with and without CCPP infection, HP had the lowest sensitivity (Se = 81.6%) and Fb had the lowest specificity (Sp = 85.0%) among the APPs parameters tested. However, PCT showed the highest Se (100%) and Sp (95.0%) to detect goats with and without CCPP infection among tested parameters. Conclusively, this study endorses the significance of selected APPs and PIC as additional screening diagnostic parameters for naturally occurring CCPP in goats. However, it does not replace traditional methods for diagnosis of CCPP in goats. Furthermore, APPs and PIC have an important role in disease pathogenesis in goats.

Inflammation-inducing Factors of Mycoplasma pneumoniae

Mycoplasma pneumoniae, which causes mycoplasmal pneumonia in human, mainly causes pneumonia in children, although it occasionally causes disease in infants and geriatrics. Some pathogenic factors produced by M. pneumoniae, such as hydrogen peroxide and Community-Acquired Respiratory Distress Syndrome (CARDS) toxin have been well studied. However, these factors alone cannot explain this predilection. The low incidence rate of mycoplasmal pneumonia in infants and geriatrics implies that the strong inflammatory responses induced by M. pneumoniae coordinate with the pathogenic factors to induce pneumonia. However, M. pneumoniae lacks a cell wall and does not possess an inflammation-inducing endotoxin, such as lipopolysaccharide (LPS). In M. pneumoniae, lipoproteins were identified as an inflammation-inducing factor. Lipoproteins induce inflammatory responses through Toll-like receptors (TLR) 2. Because Mycoplasma species lack a cell wall and lipoproteins anchored in the membrane are exposed, lipoproteins and TLR2 have been thought to be important for the pathogenesis of M. pneumoniae. However, recent reports suggest that M. pneumoniae also induces inflammatory responses also in a TLR2-independent manner. TLR4 and autophagy are involved in this TLR2-independent inflammation. In addition, the CARDS toxin or M. pneumoniae cytadherence induces inflammatory responses through an intracellular receptor protein complex called the inflammasome. In this review, the inflammation-inducing factors of M. pneumoniae are summarized.

Immunomodulating effect of inositol hexaphosphate against Aeromonas hydrophila-endotoxin

The present study was carried out to evaluate the effect of inositol hexaphosphate (IP6) administration on endotoxemia as an example of the systemic inflammatory response. Mice were divided into three groups as follows: First group, remained as a naive group injected intraperitoneally (i.p.) with PBS (pH 7.4; 0.2 ml/mice) at intervals parallel to the treated groups. The second group was injected i.p. with the lipopolysaccharide (LPS) of Aeromonas hydrophila once a week for four weeks at a dose of LPS suspension: 20 mg/kg mice/week. The third group was injected with the same LPS dose and synergistically intubated with IP6 three times a week for four weeks at a total dose of 4 0mg/kg. At different experimental periods (1, 2, 3 and 4 weeks), six animals from each group were sacrificed under mild diethyl ether anesthesia. Blood and sera were taken for the estimation of phagocytic activity, electrophoretic pattern of proteins and immunoglobulin levels. Also, a slice of liver was homogenized to estimate the respiratory burst enzymes activities and nitric acid synthesis. Histopathological changes of hepatic tissues were investigated. In the LPS-treated group, marked increase in the phagocytic activities and nitric oxide synthesis, and a decrease in hepatocyte catalase, total peroxidase and superoxide dismutase activities were observed. The histopathological features revealed a degeneration and highly mitotic division within the hepatic nuclei in addition to some karyomegaly and nuclear pyknosis. During the treatment period, liver sections of the LPS+IP6 group showed somewhat regenerative features. Reduction in the toxicity of free radicals by IP6 was observed and the IP6 effect seemed to be responsible for the observed ameliorative influence.

Isolation, structure elucidation, and synthesis of a macrophage stimulatory lipopeptide from Mycoplasma fermentans acting at picomolar concentration

Macrophages are typically stimulated by components of microbial cell walls. Surprisingly, cell wall-less mycoplasmas can also very efficiently stimulate macrophages. We showed recently that mycoplasma-derived lipopeptides constitute the active principle. We have now isolated a clone of Mycoplasma fermentans expressing mainly one macrophage-stimulating lipopeptide. This lipopeptide was detergent-extracted and isolated by reversed-phase high-performance liquid chromotography, using nitric oxide release from C3H/HeJ mouse macrophages as bioassay for detection. In contrast to "conventional" bacterial lipoproteins, this lipopeptide had a free NH2 terminus. Amino acid composition, sequence, and the molecular weight of 2,163. 3 are consistent with the following structure: S-(2, 3-bisacyloxypropyl)cysteine-GNNDESNISFKEK with one mole C16:0, and a further mole of a mixture of C18:0 and C18:1 fatty acid per lipopeptide molecule. The sequence could not be found in either the protein identification resource nor the Swiss Prot data bank. We named this 2-kD lipopeptide, macrophage-activating lipopeptide-2 (MALP-2). Synthetic dipalmitoyl MALP-2 and mycoplasma-derived MALP-2 were compared with the bioassay. Both lipopeptides showed an identical dose dependency with a half-maximal response at 10(-11) M concentration. MALP-2 may be one of the most potent natural macrophage stimulators besides endotoxin.

Modulation of Forssman glycosphingolipid expression by murine macrophages: coinduction with class II MHC antigen by the lymphokines IL4 and IL6

In contrast to murine spleen M phi, resident peritoneal M phi from health mice express very little Forssman glycolipid antigen (Fo). The following experiments suggest that Fo expression by peritoneal M phi may be associated with inflammation. Balb/c and CBA/J mice were given inflammatory stimuli by i.p. injection of live BCG, thioglycollate (TG), Corynebacterium parvum (CP), proteose peptone (PP), or LPS. Control animals received pyrogen-free saline. Expression of Fo and Ia antigen by peritoneal M phi was determined by immunofluorescence after 4 d. Application of TG or CP led to an up to 30-fold increase in Fo+, Ia+ double positive M phi over that in control animals. LPS caused mainly an increase in the percentage of double-positive M phi, whereas no effects were seen in BCG or PP treated animals. To clarify the possible involvement of cytokines in this process and to identify these, the effects of LPS and various cytokines on in vitro induction of Fo and Ia expression were studied in further experiments. LPS, IL6, and IL4 caused induction of up to 15% Fo+ and Ia+ M phi after a 4 d culture period. M phi colony stimulating factor (M-CSF) from lung-conditioned medium was also moderately active. IL1, TNF, and IL2 had no influence, whereas IFN-gamma only induced Ia. For a successful in vitro induction of Fo and Ia, a prior priming of the mice with PP appeared mandatory. This suggests that only M phi of a certain developmental stage can acquire Fo under the influence of the appropriate cytokines. The data may provide the first evidence for cytokine-mediated modulation of a glycolipid antigen of known chemical structure.

Control of IgE responses

Peyer's patches (PP) in germ-free rats (GF) and in the hyper-IgE syndrome patient (HIES) differ from their conventional rat (C) and healthy human (HH) counterparts in that GF rats contained fewer (two-fold) PP and none was detected in HIES. Existing PP in GF rats had reduced cellularity (three-fold) and different B and T cell subsets: high numbers of IgE-bearing (sIgE+) B cells (approximately 15% of total cells), one-half of which also expressed sIgA, were present in GF rat PP while none was detected in C rat PP (less than 1%). GF rat PP also contained elevated numbers of sIgA+ cells and decreased sIgM+ cells, with elevated numbers of sThy 1+ RT 7.1+ Ig- T cells (suppressor phenotype) and reduced sThy 1- RT 7.1+ Ig- T cells (helper phenotype). The cellular composition of GF rat PP was converted to that resembling a C rat within 18 hr after (a) use of standard (unautoclaved) chow; (b) feeding with certain bacteria or "working" bacterial cell wall components (BCWC) and synthetic derivatives, murein, MTP-PE, and norMDP, but not with LPS, core lipid A, or lipoprotein; BCWC had no effect if injected intravenously; or (c) thymectomy. Each procedure resulted in (i) elimination of sIgE+ B cells and normalization of the other isotypes, and (ii) loss of T suppressor cells and normalization of T helper cells. After treatments, no sIgE+ cells were detected in bone marrow (BM), thymus, other lymphoid organs, or blood. PP were not detected in HIES, although they were present in HH (approximately 10/individual). P blood contained two distinct sIgE+ B cell subpopulations, the apparent source of which was mesenteric lymph node (MLN), the only organ in which high numbers of these cells (35%) (five nodes examined) were detected; far fewer IgE+ cells were found in spleen (less than 5%), and none was detected in BM, thymus, other LN, or appendix, which was virtually acellular. Virtually no IgE secreting plasma cells were detected in MLN, spleen, appendix, other lymphoid organs, or in gut lamina propria. IgE+ B cells in MLN were not detected in follicles (classical B cell areas); instead, they were found in high numbers in the thymus-dependent area and in medulla. Most follicles (greater than 98%) in MLN and spleen contained intercellular IgE complexed to bacterial antigen and/or CD23 (IgE-binding factor? antigen?), but contained no germinal centers.(ABSTRACT TRUNCATED AT 400 WORDS)

Granulocyte progenitors (CFU-D) in neutrophilic leukemoid reaction are hyporesponsive to macrophage-induced inhibition

The responsiveness of marrow granulocyte progenitors (CFU-D) to macrophage-derived stimulatory and inhibitory factors has been studied using diffusion chamber technique in 12 patients with neutrophilic leukemoid reaction (with granulocyte count in the range between 10-40 G/l) and ten healthy subjects. CFU-D from patients with neutrophilic leukemoid reaction (NLR) revealed a normal reactivity to colony-stimulating activity, whereas they were hyporesponsive to macrophage-derived indomethacin-sensitive inhibition. This altered response was correlated both with the concentration of granulocyte progenitors in the S phase and with blood neutrophilic leukocytosis. In patients with higher granulocyte count and increased concentration of CFU-D during active DNA synthesis a more pronounced hyporesponsiveness of granulocyte progenitors to macrophage-induced inhibition has been found.

The lipophilic muramyltripeptide MTP-PE, a biological response modifier, is an activator of protein kinase C

The lipophilic immunomodulator MTP-PE is able to activate purified protein kinase C (PKC) by substituting phosphatidyl-serine (PS) or the synthetic diacylglycerol, DiC8, in the assay system. In addition, MTP-PE inhibited [3H]-phorbol-12, 13-dibutyrate ([3H]-PDBu) binding to PKC in a reconstituted receptor system as well as on intact cells (MCF-7). Furthermore, MTP-PE was also able to reduced the epidermal growth factor binding of MCF-7 cells to an extent similar to that found with DiC8 or PDBu. These data indicate that MTP-PE is able to compete for the phorbol ester binding site on PKC both in vivo and in vitro. The components of the MTP-PE molecule, MTP (muramyl-tripeptide) and PE (phosphatidylethanolamine) exerted only marginal effects on PKC activity, did not affect the phorbol ester binding of PKC and the EGF binding of intact MCF-7 cells. Our results suggest that only the complete molecule of the immunomodulator MTP-PE is able to interact with PKC.

Stimulatory effects of muramyl dipeptide and its butyl ester derivative on the proliferation and activation of macrophages in vitro

Muramyl dipeptide (MDP) and the butyl ester derivative, N-acetylmuramyl-L-alanyl-D-glutamine-alpha-n-butyl ester (MDP[Gln]OnBu), were shown to induce the in vitro proliferation of oil-induced guinea pig peritoneal exudate cells (PEC). Both agents induced 10-20 fold increases in tritiated thymidine incorporation in PEC cultures. The maximal effects occurred in 72 h cultures stimulated with either 0.1 microgram MDP or 10 micrograms MDP[Gln]OnBu. The mitogenic effects of MDP appeared to be mediated by a macrophage product detected in the supernatants of MDP-stimulated cultures. Supernatants of MDP- or MDP[Gln]OnBu-stimulated PEC cultures were also inhibitory to normal fibroblast growth and cytotoxic to L929 tumor cells. These results indicated that these agents may stimulate macrophages by modulating secretory functions. In addition, either peptidoglycan was capable of activating bactericidal activity in in vitro macrophage cultures. Initial studies of possible mechanisms of action revealed an early increase in the level of cyclic GMP. The possible role of cyclic GMP in mediating the stimulation of macrophage secretory processes is discussed.

Modulation of myelopoiesis in vivo by synthetic adjuvant-active muramyl peptides: induction of colony-stimulating activity and stimulation of stem cell proliferation

Modulation of myelopoiesis by three synthetic muramyl peptides was investigated in vivo. Two adjuvant-active compounds (N-acetylmuramyl dipeptide [MDP] and MDP-butyl-ester) elicited significant responses in DBA/2 mice characterized by a rise in the level of monocyte-macrophage colony-stimulating activity in serum, a proliferation of multipotential stem cells in the bone marrow, and an expansion of granulocyte-macrophage progenitors in the spleen. In contrast, the adjuvant-inactive stereoisomer MDP(D-D) induced only low levels of circulating colony-stimulating activity. Thus, MDP or MDP-butyl-ester injection could induce a greater number of macrophages and therefore enhance both specific and nonspecific immunity.

Muramyl dipeptides: prospect for cancer treatments and immunostimulation

The immunopharmacological activities of bacterial cell walls and muramyl peptides were collected in table form with a comprehensive literature. The past and present studies emphasizing the host-defense enhancing activities of muramyl peptides for antitumor immunotherapy were surveyed along three possible approaches: 1) the nonspecific enhancement of natural defense ability of host against tumor cells themselves; 2) the enhancement of nonspecific resistance of host to microbial infections which are frequently encountered and difficult to treat in the advanced stage of tumor patients; and 3) the stimulation of immunity against tumor-specific or tumor-associated immunogens. Finally, the prospects of successful antitumor immunotherapy with muramyl peptides and their derivatives was discussed.

Stimulatory effect of N-acetyl Muramyl dipeptide in vivo: proliferation of bone marrow progenitor cells in mice

The effects of single and multiple injections of N-acetyl muramyl dipeptide (MDP) on peripheral leukocytes, colony-forming cells (i.e., bone marrow granulocyte-macrophage progenitor cells), and the humoral immune response (to bovine serum albumin) were investigated in mice. Whereas low doses of MDP (0.1 to 1 mg/kg) provoked lymphocytosis, larger doses (10 mg/kg upward) resulted in lymphocytopenia and an increase in the number of young stab neutrophils and monocytes. MDP induced a dose-dependent increase in the number of bone-marrow macrophage progenitor cells, the maximum being reached by a dose around 10 mg/kg. A 50% increase in the maximum effect was produced by a dose around 0.1 mg/kg. The higher the dose, the longer the increase in these progenitor cells persisted. MDP mediated a dose-dependent antibody response to small amounts of bovine serum albumin, correlating with the proliferation of progenitor cells.

Growth regulation by macrophages

The evidence reviewed here indicates that macrophages, either acting alone or in concert with other cells, influence the proliferation of multiple types of cells. Most of the data indicate that these effects are mediated by soluble macrophage-elaborated products (probably proteins) although the role of direct cell-to-cell contacts cannot be ruled out in all cases. A degree of success has been achieved on the biochemical characterization of these factors, but such work has been hampered by the factors low specific activity in conditioned medium and the lack of rapid, specific assays. It is our belief that understanding the growth-regulating potential of macrophages is an important and needed area of research.

Production of lymphocyte activating factor in the absence of endogenous pyrogen by rabbit or human leukocytes stimulated by a muramyl dipeptide derivative

N-acetylmuramyl-L-alanyl-D-isoglutamine or MDP is a synthetic immunoadjuvant capable of inducing a febrile response in the rabbit and of eliciting production of endogenous pyrogen (EP) in vivo and in vitro. It was also shown to stimulate in vitro lymphocyte activating factor (LAF) release. After conjugation to a synthetic carrier, the pyrogenic effect of MDP is strongly enhanced. Recently, adjuvant active derivatives of MDP devoid of pyrogenicity such as MDP(Gln)-OnBu (AcMur-L-Ala-D-Gln-alpha-nbutyl ester) have become available. In the present study, their stimulating properties on rabbit peritoneal exudate cells or human peripheral blood mononuclear cells were simultaneously evaluated by testing lymphocyte activating property and pyrogenic effect of the culture supernatant. In both types of cell cultures, whereas MDP elicited dual effects, the nonpyrogenic analog MDP(Gln)-OnBu produced LAF without detectable pyrogenicity even when a very sensitive assay (intracerebroventricular administration) was used. In contrast, conjugated MDP was capable of inducing the production of endogenous pyrogen in rabbit cell cultures with no or little LAF release. These results argue against the possibility that a single factor is responsible for both LAF and EP activities.

Regulation of plasminogen activator secretion in mouse peritoneal macrophages. II. Inhibition by immunomodulators of bacterial origin

Two classes of immunomodulators of bacterial origin, peptidoglycan derivatives and lipopolysaccharides, are able to block in vitro the production of plasminogen activator by elicited macrophages: the release of the enzyme into the medium is inhibited and the intracellular activity reduced. In the case of peptidoglycan derivatives, high molecular weight compounds like WSA (water-soluble adjuvant) are stronger inhibitors than small molecules like MPP (muramyl pentapeptide). MDP (muramyl dipeptide) gives partial inhibition only. WSA (at 100 micrograms/ml) completely inhibits plasminogen activator production; the inhibition is reversible and specific. LPS is active at low concentrations (25-100 ng/ml). At concentrations higher than 50-100 ng/ml the action of LPS becomes irreversible and less specific. Peptidoglycan-derived immunomodulators can inhibit plasminogen activator production in the presence of polymixin B or in the case of macrophages obtained from C3H/HeJ mice; LPS is inactive under such conditions.

Evidence from a carbohydrate incorporation assay for direct activation of bone marrow myelopoietic precursor cells by bacterial cell wall constitutents

The stimulation of incorporation of [3H]galactose into membrane glycoconjugates, measured in a precipitation test, was used as a criterion for activation of bone marrow cells. In this assay, purified bacterial lipopolysaccharide, lipoprotein, and murein monomer and dimer fragments all activated rat bone marrow cells in vitro. The response was dose dependent, followed a defined time course, and was not serum dependent. O-Acetylated murein dimer fragments from Proteus mirabilis were much less active than their unsubstituted counterparts, indicating a structural specificity for murein activation. Removal of adherent and phagocytizing cells from the marrow suspensions did not alter these results. The labeled, activated cells constituted a distinct population of buoyant density 1.064 to 1.069 g/cm3 when centrifuged on a continuous gradient of Percoll. Enrichment of the target cell population was achieved by a combination of adherent cell removal and discontinuous density gradient centrifugation to remove granulocytes and erythropoietic cells. It was concluded that a population of myelopoietic precursors could be activated by direct contact with bacterial cell wall constituents. The stimulation of galactose incorporation was not coupled to active deoxyribonucleic acid synthesis in the marrow cells. Thus, the activation was interpreted as an induction of differentiation rather than a mitotic event.

Preparation and properties of antisera to Mph-1, the mouse macrophage alloantigen

Mph-1 is an alloantigen demonstrable on mouse peritoneal macrophages. Two lines, B10M.I and C.I, have been bred for use with strains I/StDa or BALB/c to produce appropriate alloantisera. Optimal immunization procedures for production of anti-Mph-1.2 (the common antigen) are described. Antisera against Mph-1.1 have so far been obtained only erratically. Antisera show complement dependent cytotoxicity against normal peritoneal macrophages and cultured blood monocytes but have no obvious effect on peritoneal lymphocytes or cultured blood neutrophils. Absorption studies show that cell for cell normal peritoneum has about fifteen times more antigen than lymph node, spleen, liver or bone marrow and at least eighty times more than thymus. We were unable to use the antiserum to cause passive enhancement of skin grafts in mice.

Macrophage activation by muramyl dipeptide (MDP) without lymphocyte participation

An increase in the numbers of spread macrophages caused by macrophage stimulants was found to be a very sensitive measure for macrophage activation. Muramyl dipeptide (MDP), bacterial lipopolysaccharide (LPS), and lymphokines were found to activate macrophages dose-dependently as measured by this parameter. Macrophage activation by MDP was strictly dependent on its adjuvant-active stereochemically specific structures. Macrophage activation by MDP and LPS occurred without lymphocyte participation. It is suggested that LPS also activates macrophages via lymphocytes.

The responses of hemopoietic precursor cells in mice to bacterial cell-wall components

The influence upon different cellular and humoral parameters of hemopoiesis of three structurally unrelated, highly purified bacterial cell-wall components (BCWC) was investigated. The spleens of C57BL/6 mice assayed 6 days after the injection of either lipid A or outer-membrane lipoportein, but not murein, showed a marked increase in granulocyte-macrophage, eosinophil, and megakaryocyte progenitor cell levels. The number of pluripotent hemopoietic stem cells (CFU-S) also increased in the spleens of mice treated with either lipid A or lipoprotein. Similar results were obtained following the injection of lipoprotein or lipid A into CBA or C57BL/6.nu mice. Genetically anemic Wf/Wf mice were found to have spontaneously elevated numbers of splenic progenitor cells, which increased further after the injection of lipid A. The proportions of the different splenic progenitor cell types were similar in both untreated and lipid A treated Wf/Wf mice, and in normal littermate controls. When tested in vitro, unfractionated or partially purified post-lipid A serum was found to stimulate the growth of granulocyte-macrophage progenitor cells (GM-CFC), but no detectable stimulation of eosinohphil, megakryocyte, or erythroid progenitor cells was observed. The data suggest that the rise in splenic levels of the different progenitor cells is not mediated by the corresponding types of CSF, but more likely by proliferation and differentiation of CFU-S.

Cellular and molecular basis of the increased splenic hemopoiesis in mice treated with bacterial cell wall components

An analysis was made of the mechanisms responsible for the increased splenic hemopoiesis occurring in mice after the injection of the bacterial cell wall components lipid A and outer membrane lipoprotein. No evidence was obtained for the presence of functional lipid A receptors on hemopoietic precursor cells. Serum from lipid A-injected mice, on injection into normal mice, induced in the spleen an increased content of all hemopoietic progenitor cells. The magnitude of the response was dependent on the dose of lipid A used and the volume of serum transferred to the recipients. C3H/HeJ mice unresponsive to lipid A exhibited similar spleen changes when injected with active post-lipid A sera. Progenitor cells of all hemopoietic lineages, including multipotential hemopoietic stem cells, were involved in the response. The results suggest that a humoral factor mediates the lipid A-induced increase of splenic hemopoiesis.

Macrophage activation by muramyl dipeptide as measured by macrophage spreading and attachment

A synthetic bacterial cell wall constituent, muramyl dipeptide (MDP), was found to induce the enhancement of macrophge spreading and attachment on glass or plastic surfaces. Macrophages exposed to bacterial lipopolysaccharide or lymphokine-containing cell supernatants showed similar enhancement. This finding supports the view that MDP activates macrophages. MDP was also found to enhance the viability of macrophages but to inhibit 3H-thymidine incorporation by macrophages.

Muramyl dipeptide-induced adjuvant arthritis

Muramyl dipeptide, N-acetylmuramyl-L-alanyl-D-isoglutamine, induced adjuvant arthritis in WKA rats when injected in a water-in-oil emulsion prepared with Freund incomplete adjuvant (Difco), but not when emulsified with Drackeol and Arlacel A.

Serum of lipopolysaccharide-treated mice contains two types of colony-stimulating factor, separable by affinity chromatography

Serum from mice treated with bacterial lipopolysaccharide (LPS) was fractionated by Con A-Sepharose affinity chromatography, and assayed in vitro for colony-stimulating factor (CSF) using mouse bone marrow cells. The CSF failing to bind to concanavalin A-Sepharose (pool A) had similar biological properties to the unfractionated serum, i.e., it stimulated the formation of about equal numbers of granulocytic, mixed granulocyte-macrophage and macrophage colonies. The fraction eluted from the Con A-Sepharose column with alpha-methyl-D-glucopyranoside (pool B) had a steeper dose-response curve than either the unfractionated serum or the pool A CSF and most of the colonies were composed of macrophages. A mixture of the pool A and pool B CSFs stimulated colonies in a similar way as unfractionated serum and poolA. The apparent molecular weights of the two types of CSF were determined by two different gel-filtration procedures. Sephacryl S-200 gel-filtration suggested an apparent molecular weight of 85,000 for pool A CSF and 180,000 for pool B CSF. Gel-filtration on Sepharose CL-6B in the presence of guanidine hydrochloride (6M) yielded an apparent molecular weight of approximately 23,000 for pool A CSF and 33,000 for pool B CSF. The colony-forming cells (CFC) responding to pool B CSF were found to have a relatively high sedimentation velocity (peak sedimentation velocity 5.6--6.2 mm/hr) compared to the CFC responding to mouse-lung conditioned medium (MLCM) whose peak sedimentation velocity was between 4.0--4.5 mm/hour. The CFC responding to pool A CSF had an intermediate sedimentation velocity (peak 4.6--5.2 mm/hour). A time-course analysis of the morphology of clones or colonies in cultures stimulated with either MLCM or pool B CSF showed that the proportion of different colony types depends significantly on the incubation period and suggested that pool tb csf induced an early commitment of CFC towards macrophages differentiation.