Nasal allergy to fungi in guinea pigs

Sensitized guinea pigs produced specific IgG and IgE antibodies toward Cladosporium and Alternaria. In presence of fungal extracts, nasal mast cells degranulate. Ultrastructural modifications of the cells during degranulation have been established. The ciliary epithelium and the ciliary beating are not affected by fungal allergens.     

Pericellular substrates of human mast cell tryptase: 72,000 dalton gelatinase and fibronectin.

Migrating cells degrade pericellular matrices and basement membranes. For these purposes cells produce a number of proteolytic enzymes. Mast cells produce two major proteinases, chymase and tryptase, whose physiological functions are poorly known. In the present study we have analyzed the ability of purified human mast cell tryptase to digest pericellular matrices of human fibroblasts. Isolated matrices of human fibroblasts and fibroblast conditioned medium were treated with tryptase, and alterations in the radiolabeled polypeptides were observed in autoradiograms of sodium dodecyl sulphate polyacrylamide gels. It was found that an M(r) 72,000 protein was digested to an M(r) 62,000 form by human mast cell tryptase while the plasminogen activator inhibitor, PAI-1, was not affected. Cleavage of the M(r) 72,000 protein could be partially inhibited by known inhibitors of tryptase but not by aprotinin, soybean trypsin inhibitor, or EDTA. Fibroblastic cells secreted the M(r) 72,000 protein into their medium and it bound to gelatin as shown by analysis of the medium by affinity chromatography over gelatin-Sepharose. The soluble form of the M(r) 72,000 protein was also susceptible to cleavage by tryptase. Analysis using gelatin containing polyacrylamide gels showed that both the intact M(r) 72,000 and the M(r) 62,000 degraded form of the protein possess gelatinolytic activity after activation by sodium dodecyl sulphate. Immunoblotting analysis of the matrices revealed the cleavage of an immunoreactive protein of M(r) 72,000 indicating that the protein is related to type IV collagenase. Further analysis of the pericellular matrices indicated that the protease sensitive extracellular matrix protein fibronectin was removed from the matrix by tryptase in a dose-dependent manner. Fibronectin was also susceptible to proteolytic degradation by tryptase. The data suggest a role for mast cell tryptase in the degradation of pericellular matrices.     

The influence of level of infection of rats with Nippostrongylus brasiliensis on the haematology and phospholipase activity and mast cell numbers in the small intestine and colon

The haematology and phospholipase activity and mast cell numbers of the small intestine and colon of rats was studied 10 days after infection with various numbers of larvae of N. brasiliensis. A significant reduction in the RBC occurred after infections with 200 and 5000 larvae but not with 1000 larvae. Hb was significantly reduced after infection with 200 larvae and increases in the MCV and MCH indicated the development of a macrocytic anaemia. Reticulocyte count was increased at all levels of infection except after 200 larvae. WBC was increased at all levels of infection except in the 5000 larvae group. Lymphocytes were significantly increased in all groups except those infected with 5000 larvae. Neutrophils increased only at the lower levels of infection. The most marked changes occurred in eosinophil numbers, significant increases occurring with increasing levels of infection. However, after infection with 5000 larvae the numbers were significantly lower than after infection with 200 or 1000 larvae. Phospholipase activity, which is believed to be related to tissue eosinophil levels, was significantly increased at all infection levels in the proximal small intestine. Significant increases in the distal ileum and colon occurred mainly after infection with 1000 and 5000 larvae. Mast cell numbers did not change significantly at any infection level. It is suggested that the pathology observed, here in the form of anaemia, is multifactorial in origin and is largely a function of the immune response, the development and expression of which is dependent on the level of infection, with suppression of immune damage occurring at the high levels of infection when pathogenesis may involve a direct effect of the worms.     

Histopathological and ultrastructural studies of cutaneous reactions elicited in naive and chronically infected mice by invading schistosomula of Schistosoma mansoni

Naive and chronically infected CBA mice were challenged percutaneously with cercariae and biopsied at varying times thereafter to provide skin samples for light and electron microscopy. The epidermis and dermis doubled in thickness in both groups; this change occurred within 3 h in immune mice and by 48 h in controls. Immune skin showed a 5-fold increase in total thickness by 72 h. Primary reaction sites were characterised by neutrophil infiltrates but in immune mice, eosinophils replaced neutrophils by day 2. Granulocytic micro-abscesses formed in the epidermis in both naive and immune skin; they entrapped cast cercarial tails and schistosomula and were eventually sloughed from the skin surface. An early loss of challenge parasites may occur in this way. Not all penetrated schistosomula completed transformation by developing the double outer membrane and these may constitute additional casualties. Schistosomula in immune but not naive skin were invested by a surface coat; this is suggested to represent an antigen/antibody complex. Significant numbers of larvae in immune skins were associated with intact granulocytes or free eosinophil granules and dead, infiltrated parasites occurred in the dermis. Such individuals may account for the additional attrition recorded in immune mice. Mast cells became associated with granulocytes in both groups of animals; they degranulated by simple exocytosis in naive skin but compound exocytosis in immune skin.     

Effects of lactation on Trichostrongylus colubriformis infections in the guinea pig

Effects of lactation on Trichostrongylus colubriformis infections in the guinea pig. International journal for Parasitology, 4: 177–181. An increase in parasite egg output occurred in lactating guinea pigs infected with Trichostrongylus colubriformis, compared with that of either non-lactating or nulliparous females similarly infected. The lactating animals carried more parasites than either of the other two groups both as fourth stage larvae 9 days after infection and as adults at the peak of egg output 19 days after infection. Both the nulliparous and the non-lactating female guinea pigs had more mast cells and eosinophils in the small intestinal mucosa than did the lactating females.The behaviour of T. colubriformis in the lactating guinea pig is considered to be substantially the same as that of the various nematodes which have been studied in the lactating ewe.     

Ultrastructure of human dermal mast cells in 29 different lysosomal storage diseases

The effect of lysosomal storage diseases on the ultrastructure of human mast cells has not previously been reported. Indeed, there has been little published evidence indicating that mast cells contain typical lysosomes. However, mast cell cytoplasmic granules contain hydrolases similar to those found in lysosomes, but which differ from lysosomal hydrolases in exhibiting optimal activity at higher pH. We therefore examined by transmission electron microscopy the dermal mast cells in 58 biopsies of patients exhibiting 1 of 29 different lysosomal storage diseases. We found mast cells containing abnormal lysosomes in 16 of these disorders. In 6 of these 16 diseases, the mast cells' cytoplasmic granules appeared normal. These observations indicate that human mast cells can contain lysosomes, and provide evidence that the enzymes affected by lysosomal storage diseases are active in mast cells.     

Reproductive collapse in European beech results from declining pollination efficiency in large trees

Climate warming increases tree mortality which will require sufficient reproduction to ensure population viability. However, the response of tree reproduction to climate change remains poorly understood. Warming can reduce synchrony and interannual variability of seed production (“masting breakdown”) which can increase seed predation and decrease pollination efficiency in trees. Here, using 40 years of observations of individual seed production in European beech (Fagus sylvatica), we showed that masting breakdown results in declining viable seed production over time, in contrast to the positive trend apparent in raw seed count data. Furthermore, tree size modulates the consequences of masting breakdown on viable seed production. While seed predation increased over time mainly in small trees, pollination efficiency disproportionately decreased in larger individuals. Consequently, fecundity declined over time across all size classes, but the overall effect was greatest in large trees. Our study showed that a fundamental biological relationship—correlation between tree size and viable seed production—has been reversed as the climate has warmed. That reversal has diverse consequences for forest dynamics; including for stand- and biogeographical-level dynamics of forest regeneration. The tree size effects suggest management options to increase forest resilience under changing climates.     

On disturbance of homeostasis in organ-cultured tissue

Summary The intact membranous rat mesentery was cultured in Eagle's minimum essential medium containing no serum or only low concentrations of serum. The procedure is in some important respects superior to previous organ culture techniques. To estimate the extent of disturbance of homeostasis of the tissue in culture, the spontaneous mast-cell histamine release was quantitated after preculture preparation of the specimens and after different intervals in culture. Also, the proliferation of fibroblasts and mesothelial cells that predominate in the mesentery was assessed at 48 h by cytofluorometric quantitation of DNA in single-tissue cells. Spontaneous histamine release was time dependent during cultivation, amounting to ca. 50% at 48 h, and was affected by the medium used for moistening the tissue before cultivation. Culturing also brought about great spontaneous increase in the proliferation of fibroblasts and mesothelial cells, the rate being related to the concentration of serum. Addition of the mast-cell secretagogues 48/80 or polymyxin B at 1 h caused rapid release of 50 to 60% of the histamine and was followed by augmented proliferation in the serum-containing media. The spontaneous increase of cell proliferation in tissue culture may be causally related to mast-cell secretion. Further studies are needed to define factors influencing the spontaneous mast-cell secretion and the mast-cell-dependent mitogenesis in normal tissue cells Supported by grants from the Swedish Medical Research Council (Project 5942) and State Board for Animal Experiments.     

The effect of streptococcus on the persistence of Brugia malayi and on the production of elephantiasis in cats

Cats were exposed to 200 Brugia malayi larvae on one hind foot over a 3 week period. Six weeks after the initial exposure to B. malayi, 10 of the cats were challenged on both hind legs with a Group G streptococcus. The remaining 10 cats were not exposed to the streptococcus. Following bacterial challenge, the B. malayi-infected leg of 9 of 10 cats displayed sequelae including erysipelas and abscesses. In addition, 5 of the affected legs had an elephantoid appearance, both by gross observation and as seen at necropsy 10 weeks after the initial B. malayi infection. The contralateral, uninfected leg of each cat remained normal in appearance. Histologic processing and examination of the elephantoid tissue showed it to be collagen; eosinophils and mast cells were plentiful in the collagen matrix. In the controls, only 1 animal displayed erysipelas and no abscesses were seen. Lymphedema seen in the B. malayi-infected leg of 5 control cats was less extensive than in uninfected cats challenged with streptococci and at necropsy no significant collagen matrix was evident. The location and number of worms in the lymphatics were noted. This study demonstrated that secondary microbial infections can contribute to the causation of elephantiasis under certain circumstances and that developing B. malayi were in some way adversely affected by the streptococcal involvement of the filaria-infected lymphatics.