LTHOUGH mtich information about mast cells has become available in recent years ( reviews by Padawer,’ Uvn#{228}s,2Riley1 ) , little is known about the function of these cells. The relation of tissue mast cells to blood basophil leukocytes has been debated since their discovery. Because of their similar staining properties, Ehrlich4 regarded the latter as blood mast cells. The availability of a...

Mast cells were identified by electronmicroscopy in the alveolar wall of the lung in 20 subjects (10 normal, 10 abnormal). A quantitative and qualitative study was made of the mast cells. In the normal lung there was an average concentration of 350 mast cells/mm2 of alveolar wall and in the abnormal 523/mm2. Mast cells occupied approximately 1.6-2.1% of the area of the alveolar wall. There was ...

The density and distribution of mast cells was assessed in skin biopsies of 118 untreated leprosy cases and 20 healthy individuals taken as controls. Mast cells were present in only small numbers in the skin biopsies of healthy individuals. Significantly higher mast cell counts were obtained in the skin lesions of indeterminate leprosy (P < 0.01). The mast cell count in the tuberculoid group wa...

Mast cells are known effector cells in allergic and inflammatory diseases, but their precise roles in intestinal inflammation remain unknown. Here we show that activation of mast cells in intestinal inflammation is mediated by ATP-reactive P2X7 purinoceptors. We find an increase in the numbers of mast cells expressing P2X7 purinoceptors in the colons of mice with colitis and of patients with Cr...

Mast cells are the major effector cells for immediate hypersensitivity and chronic allergic reactions. These cells accumulate in mucosal tissues of allergic reactions, where immunoglobulin E (IgE) is produced locally. Here we provide evidence that, in addition to antigen that can attract IgE-bound mast cells, the type of IgE molecules that efficiently activate mast cells can promote the migrati...

Angiogenesis is a complex process that involves interactions between endothelial cells and various other cell types as well as the tissue microenvironment. Several previous studies have demonstrated that mast cells accumulate at angiogenic sites. In spite of the evidence suggesting a relationship between mast cells and angiogenesis, the association of mast cells and endothelial cells remains po...

Mast cells are well positioned in host tissue for detecting environmental signals, including allergens, leading to activation of the high-affinity IgE receptor FcεRI, and initiating a signaling cascade that perpetuates the production of biologically potent mediators, including chemokines. We have identified a novel target of mast cell FcεRI activity in the transcription factor early growth resp...

Rab5 is a small GTPase that regulates early endocytic events and is activated by RabGEF1/Rabex-5. Rabaptin-5, a Rab5 interacting protein, was identified as a protein critical for potentiating RabGEF1/ Rabex-5’s activation of Rab5. Using Rabaptin-5 shRNA knockdown, we show that Rabaptin-5 is dispensable for Rab5dependent processes in intact mast cells, including high affinity IgE receptor (Fc RI...

Mast cells were observed in autopsies from 11 females and 8 males. We confirm earlier observations that mast cells are more frequent in close vicinity to MSplaques. In these plaque-border zone areas, defined as the area within 1 mm distance of the actual plaques, the average number of mast cells was 2.34/mm in males and 4.77/mm in females, which in average is appr. 10 times more than earlier ob...

Rab5 is a small GTPase that regulates early endocytic events and is activated by RabGEF1/Rabex-5. Rabaptin-5, a Rab5 interacting protein, was identified as a protein critical for potentiating RabGEF1/Rabex-5's activation of Rab5. Using Rabaptin-5 shRNA knockdown, we show that Rabaptin-5 is dispensable for Rab5-dependent processes in intact mast cells, including high affinity IgE receptor (Fceps...