Stem cell factor enhances IgE-mediated histamine and TNF-alpha release from dispersed canine cutaneous mast cells.

Stem cell factor (SCF), the c-kit receptor ligand, plays a critical role in mast cell (MC) development and differentiation. In addition, SCF has recently been found to both modulate and induce MC activation. To investigate the effect of SCF on canine cutaneous MC function, we have characterized the ability of SCF to modulate the release by mature canine MC of preformed (histamine) and newly generated (TNF-alpha) mediators. Mature MC were isolated from skin and cultured in the absence or presence of exogenous SCF (6 ng/ml) for up to 5 days and then challenged with anti-IgE (1 microg/ml) alone for 30 min or with a combination of SCF (50 ng/ml) and anti-IgE. SCF alone failed to trigger either histamine or TNF-alpha release at any time. However, we observed that SCF used as a co-stimulus significantly potentiated histamine and TNF-alpha release in canine MC activated through Fc epsilon RI regardless of whether or not SCF was added to the medium during culturing. Thus, the mean histamine release (%) and TNF-alpha production (pg/ml) were found to be significantly higher if cells were maintained in culture in SCF-supplemented medium compared with cells cultured in the absence of exogenous SCF. We also observed that MC responsiveness to immunological stimulation increased with culture time, the percentage of histamine released being higher in cells cultured for at least 3 days when compared to freshly isolated MC. Taken together these findings suggest that canine skin MC releasability can be enhanced independently either through prolonged incubation with SCF and/or through anti-IgE and SCF co-stimulation.

Gunpowder-related burns.

Gunpowder misuse is a frequent cause of burn injury in our area. The injuries are mostly minor lesions which may be treated on an outpatient basis, the more serious injuries need surgical treatment. Experience of the management of these burns is reported by reviewing 123 clinical charts of patients admitted between 1983 and 1990. The most frequent victims are teenage males who are involved mainly in accidents in the street. The most serious burns followed work-related accidents, with a fatal outcome in 47 per cent of the patients. The serious burns are usually deep dermal or full skin thickness. A common pattern affects groins, genitalia, hypogastrium and hands, and are produced when fireworks ignite in the pockets of the patient's trousers. The management of these lesions does not differ from burns caused by other agents, although attention should be paid to the presence of associated lesions, chiefly to eyes, ears and hands, due to the shockwave and shrapnel.