Journal of the Reticuloendothelial Society最新文献

The purpose of these studies was to determine whether various immunomodulators such as lipopolysaccharide (LPS), lymphokines with macrophage activation factor (MAF), or muramyl dipeptide (MDP) could activate the tumoricidal properties in LPS-responsive C3H/HeN and LPS-unresponsive C3H/HeJ mice. In all studies we examined the interaction of the different immunomodulators in a free form or encapsulated within liposomes (multilamellar vesicles) with alveolar macrophages (AM) and/or peritoneal exudate macrophages (PEM). In vivo infection with viable Mycobacterium bovis, strain BCG, induced the development of highly activated macrophages from C3H/HeN mice, yet only marginally activated macrophages from C3H/HeJ mice. In vitro incubation with MAF or LPS rendered AM and PEM from C3H/HeN, but not C3H/HeJ, mice tumoricidal. The failure of C3H/HeJ macrophages to respond to LPS stimulation was due to an intracellular defect. C3H/HeJ macrophages bound fluorescein-conjugated LPS to the same extent as that found for C3H/HeN macrophages. Furthermore, LPS encapsulated in liposomes activated C3H/HeN but not C3H/HeJ AM and/or PEM. Macrophages from both strains could be rendered highly tumoricidal following interaction with free MDP or following endocytosis of liposomes containing MDP or MAF. These results indicate that the inability of C3H/HeJ macrophages to respond to LPS stimulation is specific and that the activation of macrophages by different immunomodulators could occur by different pathways.

The role of nonspecific macrophage activation in the destruction of treponemes needs to be defined. Studies have been hindered by an inability to confirm that macrophages have enhanced bactericidal activity at the site of treponemal infection. We show that subcutaneous and intravenous vaccination with BCG (Mycobacterium bovis) induces macrophage activation in hamsters, as determined by an enhanced ability to suppress the growth of Listeria monocytogenes in the livers, spleens, and inguinal lymph nodes. However, hamsters challenged in the inguinal region with Treponema pertenue during periods of enhanced microbial resistance (3 to 8 weeks after BCG vaccination) developed lesions faster and with more necrosis. Increased numbers of treponemes were recovered from the regional lymph nodes of BCG-vaccinated hamsters than from nonvaccinated controls, although the differences were not statistically significant. No pathological differences were detected in BCG-vaccinated and non-vaccinated hamsters challenged with Treponema pallidum Bosnia A. These studies demonstrate that BCG vaccination influences the pathogenesis of some treponemal diseases without inducing macrophage-mediated treponemicidal activity.

The ability of subpopulations of murine spleen cells enriched for macrophages to function as stimulator cells in the F1 x parent-hybrid mixed leukocyte reaction (F1 x P MLR) was assessed. Suspensions of F1 splenic adherent cells--depleted of T cells, B cells, and dendritic cells--were separated into four density-dependent subpopulations on discontinuous gradients of Percoll, and the cells were examined for macrophage characteristics, the presence of la antigen, and their ability to stimulate in the F1 x P MLR. The least dense subpopulation was the most highly enriched with nonspecific esterase-positive (NSE+), phagocytic, and Fc and complement receptor-bearing cells, by comparison with the denser subpopulations. All subpopulations contained similar proportions of Ia+ cells. When the MLR stimulatory activity of the subpopulations was tested with suspensions of parental responder cells, the level of stimulation was directly proportional to the content of NSE+la+ cells in the subpopulations. The densest subpopulation contained no NSE+ cells but did contain la+ cells, which did not induce a MLR. Thus, although necessary for an MLR, la-bearing splenocytes were not by themselves adequate to stimulate the reaction. Rather, cells had to be both NSE+ and la+, indicating that a NSE+ cell-derived factor is involved in this in vitro correlate of cell-mediated immunity. For MLR stimulatory activity, the subpopulations of NSE+la+ cells appear to be functionally homogeneous.

The murine macrophage-like cells NCTC 1469, J774A, WEHI-3, IC21, and P388D1, were compared with respect to their peroxidatic activity, display of cell surface antigens, and production of colony-stimulating factor. Peroxidatic activity was demonstrated in the nuclear envelope and in the cisternae of the rough endoplasmic reticulum of NCTC 1469 cells, J774A cells, and P388D1 cells, and in granules of WEHI-3 cells and IC21 cells. Colony-stimulating factor was produced only by WEHI-3 cells. NCTC 1469 and IC21 cells had a weak expression of M1/69 and Mac-1 antigens, whereas P388D1 cells expressed these antigens at a high level. WEHI-3 cells expressed M1/69 at a high level and Mac-1 at a low level, whereas J774A cells had an opposite expression T 200, Pgp-1, and ThB antigens were expressed at different levels by the various cell lines, without overt correlation among themselves or with the expression of M1/69 or Mac-1 antigens. These data suggest that macrophage-like cell lines cannot be placed in a maturation/differentiation lineage.

Data are summarized suggesting an inherent heterogeneity of bone marrow macrophage precursor cells. The possible relationship of this heterogeneity with the functional heterogeneity of blood monocytes and tissue macrophages under normal conditions and at an inflammatory site is discussed. A hypothesis suggesting that the bone marrow compartment is involved in the generation of macrophage heterogeneity is presented.

Human glomerular epithelial and mesangial cells were grown in vitro and shown to have distinctive morphologic and functional characteristics. Glomerular epithelial cells or mesangial cells cultured in wells of flat-bottom microtiter plates were treated for 4 hr with dialyzed macrophage supernatants obtained from cultures of mouse peritoneal macrophages or human peripheral monocytes. DNA, RNA, and protein synthesis were evaluated by incorporation of radioactive precursors. Macrophage supernatants stimulated RNA and protein synthesis in epithelial cells but failed to stimulate DNA synthesis. The macrophage factor(s) showed a dose-response activity, was nondialyzable, was destroyed by freezing and thawing, and did not seem to be species specific. In contrast to the results obtained with glomerular epithelial cells, mesangial cell DNA synthesis was stimulated by macrophage supernatants. The observed metabolic effects of macrophage products on glomerular cells in vitro are consistent with observations of in vivo glomerular response to injury in which epithelial cells may be activated to form new basement membrane while mesangial cells may respond by proliferating. These data further support the theory of macrophage involvement in the pathology of glomerulonephritis.

Lung macrophages from normal guinea pig lungs were separated from bronchoalveolar cells into three fractions according to buoyant density by centrifugation on continuous iso-osmotic gradients of Percoll [3]. A reproducible pattern of functional activity distinguished these three macrophage fractions. With increasing density and decreasing cell size, the respective fractions exhibited increased stimulated migration, superoxide anion release and pinocytosis, and increased protein concentration of the cells. These differences, coupled with previous observations that these fractions also exhibited morphological and cytochemical differences [3], support the notion that these fractions of macrophages may represent different stages of maturation (or differentiation) of alveolar macrophages in the lungs of normal guinea pigs.

Both immune complexes and carbon particles were trapped in spleen follicles soon after intravenous injection. The localization pattern of carbon particles and immune complexes were identical 24 hr after injection. Since there is no reason to believe that lymphocytes are involved in the transport of carbon particles from the marginal zone towards the follicle centers, these results indicate that follicular trapping is based on a purely mechanical process. Pretreatment with endotoxin completely prevented the trapping of immune complexes but not carbon particles. Endotoxin administered after the injection of immune complexes caused the rapid removal of trapped complexes from the follicles. However, the effect of endotoxin on trapped carbon particles was less pronounced. Apart from a mechanical trapping of diffusing compounds in the follicular web, a distinct phase is suggested in which immune complexes are fixed to and retained on the surface of the follicular dendritic cells.

Cells recovered by lavage from lungs of normal guinea pigs were centrifuged on continuous density gradients of colloidal silica (Percoll). The gradient was divided into six fractions based on the banding pattern of cells. This pattern was highly reproducible from animal to animal. Cell types in the fractions were identified by morphological and cytochemical criteria and the volume of the cells was determined by measuring their diameter and tritiated water space. More than 70% of the cells put on the gradient were recovered in the six fractions and there was no selective loss of cell types. Macrophages comprised more than 95% of the cells in fractions 3, 4, and 5. These fractions were of intermediate density (1.037-1.078 gm/ml) and together contained more than 85% of the recovered macrophages. Fraction 6 (density 1.078-1.130 gm/ml) was enriched for lymphocytes and granulocytes. Macrophages in fraction 5 were smaller, had more densely staining cytoplasm, and exhibited more nonspecific cytoplasmic esterase activity than macrophages in other fractions (5 greater than 4 greater than 3 greater than 2). These results indicate that density-gradient centrifugation on Percoll is an efficient method for purifying guinea pig alveolar macrophages and demonstrate that macrophages that differ in bouyant density also differ in morphologic and cytochemical properties. In a companion paper we report that macrophages in fractions 3, 4, and 5 differ functionally as well [9].