Nerve growth factor and neuronal cell death.

The regulation of neuronal cell death by the neuronotrophic factor, nerve growth factor (NGF), has been described during neural development and following injury to the nervous system. Also, reduced NGF activity has been reported for the aged NGF-responsive neurons of the sympathetic nervous system and cholinergic regions of the central nervous system (CNS) in aged rodents and man. Although there is some knowledge of the molecular structure of the NGF and its receptor, less is known as to the mechanism of action of NGF. Here, a possible role for NGF in the regulation of oxidant--antioxidant balance is discussed as part of a molecular explanation for the known effects of NGF on neuronal survival during development, after injury, and in the aged CNS.

Histology of normal aortas in non-human primates with emphasis on diffuse intimal thickening (DIT).

Little information is available on the histology of the normal aorta in non-human primates, despite their extensive use in atherosclerosis research. This paper consists of a detailed histologic description of normal aortas from 28 non-human primates, including 20 species. Medial and adventitial coats were essentially normal in all animals, and the former were composed of lamellar units similar in structure to those described in detail by other investigators. Intimal thickenings were present in 24 of the 28 individuals. These thickenings were similar in morphology to those of diffuse intimal thickening (DIT) in humans and other animals, and were more prevalent in older animals and in larger animals. The thickenings were not more prevalent or more pronounced in any particular region of the aorta, and their distribution did not provide a clue as to their etiology. Findings suggested that the thickenings underwent recognizable states of growth and maturation, and that growth was accomplished by the addition of smooth muscle cells at the intimomedial junction.

Histology of normal aortas in birds with emphasis on intimal thickening.

Published studies of normal aortic structure have been infrequent in birds despite a high prevalence of spontaneous atherosclerosis relative to mammals, and a feeling that this prevalence of atherosclerosis might be related to the pecularities of aortic structure in birds. We describe aortic structure in 26 birds, including 22 species and 12 families. All aortas had a complex structure similar to hat of the White Carneau pigeon which has been carefully studied. Diffuse intimal thickening (DIT) was found in the elastic zones in 22 of the 26 aortas. This lesion has not been previously described as such, and consisted of multiple longitudinally oriented elastic laminae apparently synthesized by interlamellar connective tissue cells, the latter being peculiar to the avian aorta. Focal intimal thickenings were very common in the non-elastic zones of the aortas, and were composed of smooth muscle cells and elastic laminae similar to the DIT of mammals. Their location suggested that blood flow patterns might be an important influence in their development. The fact that atherosclerotic lesions usually occurred in the non-elastic zones of the avian aorta suggested that some property of the elastic zone or the interlamellar connective tissue cells might inhibit the development of atherosclerosis.

Immunocytochemical localization of monoamine oxidases A and B in human peripheral tissues and brain.

Monoamine oxidases (MAO; EC 1.4.3.4.) A and B occur in the outer mitochondrial membrane and oxidize a number of important biogenic and xenobiotic amines. Monoclonal antibodies specific for human MAO A or B and immunocytochemical techniques were used to visualize the respective enzymes in human placenta, platelets, lymphocytes, liver, brain, and a human hepatoma cell line. MAO A was observed in the syncytiotrophoblast layer of term placenta, liver, and a subset of neurons in brain, but was not observed in platelets or lymphocytes, which are known to lack type A enzyme. MAO B was observed in platelets, lymphocytes, and liver, but not in placenta, which contains little or no MAO B. MAO B was also observed in a subset of neurons in the brain that was distinct from that which contained MAO A. MAO A and MAO B were also observed in some glia. Unlike most tissues examined, liver cells appeared to contain both forms of the enzyme. These studies show that MAO A and MAO B can be specifically visualized by immunocytochemical means in a variety of human cells and tissues and can provide a graphic demonstration of the high degree of cell specificity of expression of the two forms of the enzyme.

In vitro leukemic cell differentiation in metal-depleted media.

Lymphocytes of children with T cell and pre-B cell acute lymphocytic leukemia (ALL) were cultured in media with different concentrations of Fe, Cu and Zn to detect a possible effect of these ions on leukemic cells. Thymidine uptake was elevated in non-mitogen stimulated ALL cells and increased after mitogen stimulation, whereas intracellular ferritin, Fe and Cu, elevated before culture, decreased thereafter; pre-B ALL cells, positive only for cytoplasmic mu chains, became positive for surface immunoglobulins and released a detectable amount of them; low T4/T8 ratio in cells from T cell ALL returned to normal values after culture. These findings were present only in media with minimal concentrations of Fe, Cu and Zn and suggest that regulation of intracellular levels of these metals may induce some differentiation of leukemic cells.

Trace metals, surface receptors and growth of human normal and leukemic lymphocytes.

To evaluate the modulatory effects of trace metals on lymphocyte growth and maturation, thymidine uptake (TU), protein, ATP, Fe, Cu, Zn, ferritin, CD3, CD4, CD8 antigens, surface transferrin receptors (TFR) and interleukin 2 receptors (IL2R) were assessed in normal and T cell leukemia human lymphocytes, cultured in media with varying Fe, Cu and Zn concentrations [Me]. In normal lymphocytes in media with optimal [Me], all values increased significantly after PHA stimulation, except for intracellular metal concentration and CD3+, CD4+, CD8+ cells which were unchanged. In media with low or high [Me], all parameters except for CD8+ cells were decreased. In unstimulated ALL lymphocytes grown in media with optimal [Me], TU, protein, ATP, CD4+, Fe, Cu and ferritin were higher and Zn and CD8+ lower than in unstimulated normal cells: they did not change after PHA stimulation, except in media with low [Me], in which they approached the values of stimulated normal lymphocytes. TFR and IL2R for ALL cells were high in all media: IL2R but not TFR increased after PHA stimulation. No relationship between IL2R and TFR was demonstrable in any media. We conclude that the response of normal lymphocytes to stimuli is sensitive to variation in trace metals, whereas this response, absent in ALL lymphocytes, reappears only in media with low [Me] and is independent from TFR.

Renal tubule brush border antigens: failure to confirm a pathogenetic role in human membranous glomerulonephritis.

Biopsies from 60 patients with membranous glomerulonephritis (MGN) were examined for the presence of renal tubular brush border antigens (BBAs) in immune complexes. Eluted and uneluted tissue sections were stained with fluoresceinated antibody to human BBA preparations. In no instance were BBAs found in glomerular deposits. The specificity of antisera and immunopathologic findings were verified by appropriate controls. The results failed to corroborate a role for BBAs in the pathogenesis of human MGN.

The distribution of uterine glycogen during early pregnancy in the young and senescent golden hamster.

Glycogen distribution in the uterus of young and old hamsters was examined histochemically during the implantation of the embryo. Decidual cells and glycogen first appeared at 96 hours (post-ovulation) in the young animal. Decidualization did not occur in the senescent animal until 108 hours of development and the appearance of glycogen in the antimesometrial stroma was further delayed until 120 hours of development in the aged female. By 132 hours glycogen synthesis in the antimesometrial decidua was similar in both groups. Mesometrial glycogen synthesis in the aged animal continued to lag behind that of the young animal throughout the period investigated. The role of the delayed decidual cell response and the appearance of glycogen as possible causal factors in the observed decreased reproductive output in senescent animals is discussed.

The influence of nerve growth factor on the in vitro proliferative response of rat spleen lymphocytes.

Splenic lymphocytes and accessory cells express receptors for nerve growth factor (NGF), a well-characterized neurotropic peptide that influences the development and survival of neuronal elements in the central and peripheral nervous systems. In the present study, we report that when rat splenic mononuclear cells (MC) are incubated in the presence of NGF, a dose-dependent increase in DNA synthesis occurs during 96-120 hours of culture as measured by 3H thymidine (3H-Thd) uptake. The minimal molar concentration of NGF at which the increased proliferative response of the cells (3.7 nM) is seen corresponded to the equilibrium disassociation binding constant of the MC (Kd = 2.5 nM), suggesting that the response was a consequence of receptor-ligand interaction. In addition, NGF was able to potentiate the lymphoproliferative response to several T-cell and B-cell mitogens. Significantly increased 3H-Thd uptake by NGF-stimulated cells was noted for concanavalin A (Con A), phytohemagglutinin (PHA), and lipopolysaccharide (LPS), particularly at suboptimal dosages of mitogen. Thus it appears that the NGF receptors on rat splenic MC are physiologically relevant and that NGF can modulate proliferation of T- and B- cells.

Anti-inflammatory properties of human milk.

An hypothesis was developed which predicts that human milk protects against infections of the alimentary tract of the breast-fed infant by non-inflammatory mechanisms. Human milk is poor in the initiators and mediators of inflammation and rich in anti-inflammatory agents. Furthermore, many of the anti-inflammatory agents are comparatively resistant to digestive enzymes and therefore might be expected to remain active in the gastrointestinal tract of the recipient. Further studies of these factors in in vivo models will be required to validate the hypothesis.

Decreased response of human milk leukocytes to chemoattractant peptides.

To test the hypothesis that neutrophils and macrophages in human milk may not defend by classical inflammatory mechanisms, experiments were conducted to ascertain whether adherence, orientation, and directed motility of these leukocytes would be enhanced by exposure to chemoattractant peptides including N-formyl-L-methionyl-L-phenylalanine and N-formyl-L-methionyl-L-leucyl-L-phenylalanine and C5a generated from zymosan activated human serum. Adherence and spatial orientation were tested on coverglasses and in Zigmond chambers, and chemotaxis was examined by Boyden chambers and a subagarose technique. Whereas, the adherence, orientation, and directed movement of adult peripheral blood neutrophils and monocytes were significantly enhanced by those chemotactic agents, human milk leukocytes failed to respond. The failure of the response of human milk leukocytes was not due to alterations in maternal peripheral blood leukocytes but appeared to be due partially to inhibitors in human milk. The experiments suggest that human milk leukocytes may be modified in the mammary gland to protect by noninflammatory mechanisms.

Expression of nerve growth factor receptors by human peripheral blood mononuclear cells.

In the rat, nerve growth factor (NGF) has been shown to affect immune reactivity by binding to cell surface receptors on a subpopulation of splenic mononuclear cells. This binding occurs in a specific and saturable fashion to what appear to be low-affinity (type II) NGF receptors (NGFR). Immunofluorescence studies here showed that NGFR are also present on a proportion of human peripheral blood mononuclear cells (PBMC). Equilibrium binding studies demonstrated that the binding of NGF to its receptors on PBMC occurs with a single equilibrium binding constant (mean) of 2.11 X 10(-9) M. The number of receptors per cell was determined to be approximately 6.94 X 10(3) receptors/cell. These results would suggest a role for NGF in the regulation of immune function in man, as well as in animals.

Receptors for nerve growth factor on rat spleen mononuclear cells.

Considerable evidence is mounting to support the concept of a modulatory role for the brain and neuroendocrine system on the immune response. This neuroimmunomodulation occurs in part through the interaction of specific neurosubstances with receptors on lymphocytes and monocytes. Nerve growth factor (NGF) is a neuronotrophic factor necessary for the development and maintenance of sympathetic and embryonic sensory neurons. This trophic effect is initiated through binding of NGF at specific cell surface receptor sites on NGF-responsive cells. Several recent studies suggest that NGF may interact with cells of the immune system and may play a role in the regulation of some immunologic reactions. In this study we report on the presence of specific receptors for NGF on the surface of mononuclear cells from rat spleens. The NGF-binding sites are of the low-affinity type with Kd's in the 10(-9) M range. These receptors migrate on SDS-PAGE as two molecular species of approximately 190 and 125 kilodaltons. Our findings of receptors for NGF on lymphocytes and accessory cells support other evidence that NGF may influence immunoreactivity in vivo.