Recovery from desensitization of IgE-dependent responses in human lung mast cells.

BACKGROUND: Clinical desensitization and oral food immunotherapy are therapeutic interventions that allow individuals who react adversely to an allergen (drug or food) to be made tolerant to the allergen. However, tolerance is brief, and allergen hypersensitivity can recur within days following allergen withdrawal. OBJECTIVE: We hypothesize that the reason these treatments are temporary reflects rapid recovery of mast cells from a desensitized state. We sought to test this. METHODS: Desensitization of IgE-mediated histamine release from human lung mast cells was explored by methods that partially replicate the pattern of treatment during clinical desensitization. Specific and non-specific desensitization and changes in surface IgE were examined following desensitization. Recovery from desensitization was also studied. RESULTS: Desensitization of mast cell responses was readily induced with concentrations of antigen or anti-IgE that were suboptimal for secretion. There was little or no non-specific desensitization when lung mast cells were exposed to antigens. There was no loss of cell surface IgE following desensitization. Removing the desensitizing stimulus from the media following desensitization allowed the cells to recover with half-point of recovery of ~1.5 days and complete recovery after 5 days. Both the functional response and histamine content recovered within this time frame. The recovery appeared possible because both antigens and anti-IgE dissociated rapidly from cells after washing to remove excess stimulus. CONCLUSIONS AND CLINICAL RELEVANCE: Human lung mast cells readily recover from a desensitized state following removal of desensitizing antigen. This finding provides a potential explanation for the ephemeral nature of clinical desensitization.

Heterogeneity in the responses of human lung mast cells to stem cell factor.

BACKGROUND: Stem cell factor (SCF) is a growth factor that is involved in mast cell differentiation and proliferation. SCF primes human lung mast cells for enhanced responses to IgE-directed activation but is not generally recognized as a direct activator. SCF mediates its effects through c-kit. OBJECTIVE: The aim of this study was to reappraise the effects of SCF on human lung mast cells. METHODS: Mast cells were isolated from human lung. Mast cells were challenged with anti-IgE or SCF and the generation of histamine, cysteinyl-leukotrienes (cys-LTs) and prostaglandin D(2) (PGD(2) ) was assessed as was expression of the activation marker, CD63. The effects of c-kit inhibitors on mediator release were evaluated. RESULTS: Stem cell factor (10 ng/mL) alone was unable to induce mediator release but primed mast cells for enhanced IgE-dependent secretion. At higher concentrations (≥ 30 ng/mL), SCF had more varied effects and even when used alone was able to drive substantial levels of histamine release in about a third of all preparations studied. Similarly, SCF (100 ng/mL) alone was effective in stimulating the generation of cys-LTs in half of the preparations studied. SCF (100 ng/mL) was even more effective at stimulating PGD(2) generation as almost all preparations generated substantial quantities of the prostanoid. Mediator release induced by SCF was accompanied by the up-regulation of the activation marker, CD63. There was a positive correlation between the extent of mediator release induced by SCF and c-kit receptor expression. The effects of SCF on mediator release from mast cells were reversed by the c-kit inhibitor imatinib. CONCLUSIONS AND CLINICAL RELEVANCE: These data demonstrate that the responses of mast cells to SCF are heterogeneous. SCF can drive much greater levels of mediator release from mast cells, especially of PGD(2), than hitherto appreciated and this could be important in the context of respiratory diseases.

Sudden cardiac deaths in young British Army personnel.

Much attention has been paid to sudden cardiac death in young athletes which has led to the implementation of tighter screening controls in many sports at various levels. Less attention has been paid to this subject in young army recruits. We describe three cases of sudden cardiac death in young UK soldiers. The scale of the problem in the UK is unknown. We highlight issues regarding diagnostic testing to identify risk factors for sudden cardiac death and suggest potential additions to the current screening programme for new recruits to help increase the sensitivity of detecting cardiac pathology and reducing the rates of sudden cardiac death in this group.

Interobserver variation in the classification of thymic tumours--a multicentre study using the WHO classification system.

AIMS: To test the reproducibility of the current World Health Organization (WHO) classification of thymic epithelial tumours and to determine the level of interobserver variation within a group of pathologists, all with experience and expertise in thoracic pathology. METHODS AND RESULTS: Ninety-five thymic tumours were circulated to a group of 17 pathologists in the UK and The Netherlands over a 1-year period. Participants were asked to classify them according to WHO criteria. The diagnoses were subjected to statistical analysis and kappa values calculated. The overall level of agreement was moderate (kappa 0.45). When the categories were reduced in number by creating two groups, (A + AB + B1 + B2 and B3 + C), the level of agreement increased to 0.62. An alternative grouping (A + AB + B1 and B2 + B3 + C) increased it slightly further. The best agreement was in tumour types A and AB. Difficulties arose in distinguishing B1 tumours from B2 tumours and B2 tumours from B3 tumours. CONCLUSIONS: Although the WHO system describes a number of well-defined tumour types with clear diagnostic criteria, the overall level of agreement was moderate and improved if some groups were amalgamated.

Dilated cardiomyopathy and sudden death in a teenager with palmar-plantar keratosis (occult Carvajal syndrome).

A 16-year-old female who was diagnosed with palmar-plantar keratosis and Papillon-Lefevre syndrome in life died following a period of stress/affray. Autopsy examination revealed evidence of minor trauma and a grossly abnormal heart. The heart was sent fresh and intact to a cardiac pathologist for examination. This revealed a dilated cardiomyopathy with left ventricular fibrosis, without fatty infiltration of the right ventricle. The features were in keeping with Carvajal syndrome, a variant of Naxos disease. This rare cardiac pathology and the interaction between stress (physiological, psychological and traumatic) and natural disease are discussed. The role of prompt referral for cardiac pathology assessment and association with the genodermatoses is also considered.

National guidelines for adult autopsy cardiac dissection and diagnosis--are they achievable? A personal view.

Adult autopsy cardiac pathology has been previously a quiet backwater of ischaemic heart disease and the occasional cardiomyopathy. This has changed to an increasingly tense area, following recent genetic discoveries and some medicolegal cases. All autopsy pathologists should consider their dissection protocols and check that they are able to deliver the increasingly detailed information that clinicians, geneticists and families require. This text has suggestions about the practical realities of cardiac dissection, cardiac histology and the need for other tests alongside illustrations aimed to assist case consideration.

Influence of beta2-adrenoceptor gene polymorphisms on beta2-adrenoceptor-mediated responses in human lung mast cells.

BACKGROUND AND PURPOSE: Previous studies have shown that beta(2)-adrenoceptor-mediated responses in human lung mast cells are highly variable. The aims of the present study were to establish whether polymorphisms of the beta (2)-adrenoceptor gene (ADRB2) influence this variability in (a) beta(2)-adrenoceptor-mediated inhibition and (b) desensitization of beta(2)-adrenoceptor-mediated responses in human lung mast cells. EXPERIMENTAL APPROACH: Mast cells were isolated from human lung tissue. The inhibitory effects of the beta-adrenoceptor agonist, isoprenaline (10(-10)-10(-5) M), on IgE-mediated histamine release from mast cells were determined (n=92). Moreover, the inhibitory effects of isoprenaline were evaluated following a desensitizing treatment involving long-term (24 h) incubation of mast cells with isoprenaline (10(-6) M) (n=65). A potential influence of polymorphisms on these functional responses was determined by genotyping 11 positions, in the promoter and coding regions, of ADRB2 previously reported as polymorphic. KEY RESULTS: There was no influence of any of the polymorphic positions of ADRB2 on the potency of isoprenaline to inhibit histamine release from mast cells with the exception of position 491C>T (Thr164Ile). There was no influence of any of the polymorphic positions of ADRB2 on the extent of desensitization of the isoprenaline-mediated response following a desensitizing treatment except for position 46G>A (Gly16Arg). Analyses at the haplotype level indicated that there was no influence of haplotype on beta (2)-adrenoceptor-mediated responses in mast cells. CONCLUSIONS AND IMPLICATIONS: These data indicate that certain polymorphisms in ADRB2 influence beta(2)-adrenoceptor-mediated responses in human lung mast cells.

Basal cell carcinoma histological clearance margins: an analysis of 1539 conventionally excised tumours. Wider still and deeper?

An analysis of peripheral and deep margins of histological clearance around 1539 consecutive basal cell carcinomas excised by conventional surgery showed that 81 lesions (5.3%) were incompletely excised peripherally; 36 lesions (2.3%) were incompletely excised deeply; 13 lesions (0.8%) were incompletely excised peripherally and deeply. Nine hundred and ninety-six lesions (65%) were excised with a peripheral histological clearance margin<5mm (0.1-4.9mm), whereas 1303 lesions (85%) were excised with a deep histological clearance margin<5mm (0.1-4.9mm). Four hundred and eight lesions (27%) had a peripheral histological clearance margin of 5.0-9.9mm, whereas 170 lesions (11%) had a deep histological margin of 5.0-9.9mm. Peripheral histological clearance margins exceeded 10mm in 41 lesions (3%) and deep histological margins exceeded 10mm in 17 lesions (1%). Thus 30% of peripheral histological margins were 5mm or more but only 12% of deep histological margins were 5mm or more. Despite a relative sparing of deep tissue, incomplete excision in depth affected only 36 lesions compared with 81 incomplete peripheral excisions. Peripheral histological clearance was <5mm (0.1-4.9mm) for 55% of temple lesions, 50% of scalp lesions and 43% for limb lesions. In the cosmetically sensitive areas of peri-orbital region, nose, cheek, lip, neck and chin more than 70% of lesions were excised with a peripheral histological margin<5mm. This study of conventional surgical excision of basal cell carcinomas with an incomplete excision rate of 8% has shown that 65% of lesions were excised with <5mm histological clearance peripherally and 85% with <5mm deep clearance. These figures for 'normal tissue sacrifice' are not excessive when compared with those of 'tissue sparing' Mohs' micrographic surgery in which the operator may take a margin of several millimetres of normal tissue in the initial 'slice', or in the subsequent 'safety margin' beyond the eventual tumour free plane. However, peripheral margins did exceed 5mm in more than 30% of lesions of scalp, temple and forehead, and for these sites where even with loupe magnification the tumour edge could be difficult to define, either frozen section control or Mohs' technique, might with benefit be more often used in order to minimise normal tissue sacrifice.

Total hip replacement in a patient with systemic mastocytosis: a case report.

Systemic mastocytosis is a rare condition that often involves the bone marrow. We report the case of a patient with systemic mastocytosis who underwent total hip replacement. Technical difficulties encountered during the procedure included a narrow medullary canal and abnormally hard bone, later confirmed by laboratory measurements. Follow-up at five years showed a good clinical and radiological outcome.

Do basal cell carcinomas recur after complete conventional surgical excision?

For 1378 patients treated in the 11 years 1988-1998 by conventional excision of 1635 basal cell carcinomas, 1516 first index lesions were histologically completely excised. All patients having more than one BCC excised were identified from the data base from 1988 to 2003 to give minimum 5 years follow for last treated primary lesions in 1998. Measured clearance margins around the initial lesions at or near sites of presumptive recurrent lesions were noted and the lesions recorded photographically. All incompletely excised lesions whether or not re-excised were excluded. The median age for all patients was 70 years. Over minimum 5 years follow up, six patients developed nine subsequent lesions contiguous with the scar or graft repair of primary index lesion excision site (probable recurrences). The median interval to recurrence was 41 months (4 months-8 years 10 months), with median lateral clearance margin around the primary tumour of 2 mm (0.3-6.8 mm). A further nine patients developed 11 new lesions near (within 1cm of) the scar or graft of primary index lesion excision site (possible recurrences). The median interval to recurrence was 59 months (1 year-8 years 6 months). The median lateral clearance margin around the primary tumour was 4.1 mm (0.8-5.8 mm). For the two groups combined the maximum recurrence rate expressed as a percentage of index lesions was 1.3% (20/1516). Two thirds of possible and probable recurrences occurred in the temple and forehead, although these sites represented only 22% of all lesions, which may rather suggest new lesions in an area of field change as opposed to residual disease. The measured clearance margins reported here perhaps suggest that some original lesions may well have been completely excised primarily and many 'recurrences' were new primaries. These figures indicate there is a low order of probability for the incidence of recurrent basal cell carcinoma during minimum 5 years follow period after conventional surgical excision and conventional histological assessment of tumour resection margins.

Saphenofemoral venous channels associated with recurrent varicose veins are not neovascular.

BACKGROUND: Recurrence of varicose veins after apparently adequate surgery is common. Neovascularisation, the formation of new vascular channels between a venous surgery site and new varicosities, is thought to be an important cause of recurrence. The aim of this study was to provide histological evidence of the 'neovascularisation'process. METHOD: Tissue samples from the region of the previously ligated saphenofemoral junction (SFJ) were taken from 14 limbs with recurrent varicose veins and from nine control limbs. Tissue samples were analysed histologically for overall vascularity, and the presence of intimal circular fibrosis, intimal eccentric fibrosis, medial thickened elastosis, and thrombosis in the microscopic thin walled vessels within the tissue. The same samples were analysed immunohistoligically for S100, a neural marker, and Ki-67 (Mib 1), a marker of endothelial proliferation. Absent S100 and positive Ki-67 were considered as evidence of new vessels. RESULT: No significant difference was found between the venous recurrence and control groups in respect to histological features. S100 positive nerve fibrils were seen associated with dilated venous channels in the majority of both redo and control groups (p=1, Fisher's exact test). Only one section stained positively with Ki-67 (Mib1) in a single vascular channel for a few endothelial cells. The remaining control and redo cases were negative for Mib 1 (p=1, Fisher's exact test). CONCLUSION: We found little evidence of neovascularisation associated with recurrent varicose veins in the saphenofemoral region. The venous channels that develop at the previously ligated SFJ may represent adaptive dilatation of pre-existing venous channels (vascular remodelling), probably in response to abnormal haemodynamic forces.