Immunophenotypic analysis of the p53 gene in non-melanoma skin cancer and correlation with apoptosis and cell proliferation

BACKGROUND: Sunlight precipitates a series of genetic events that lead to the development of skin cancers such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The p53 tumour suppressor gene, which plays a pivotal role in cell division and apoptosis, is frequently found mutated in sunlight-induced skin tumours. OBJECTIVE: To investigate the immunoreactivity of the p53 gene in non-melanoma skin cancers and to correlate its expression with apoptotic and cell proliferation markers. METHODS: We analysed 35 non-melanoma tumours including 19 BCCs and 16 SCCs from sun-exposed skin areas. p53 protein expression was studied immunohistochemically using the DO7 monoclonal antibody against wild-type and mutant p53 forms. The percentage of p53-immunopositive nuclei was measured by image analysis. Cell proliferation and apoptosis were also assessed by image analysis following Ki-67 immunostaining and application of the TUNEL method on paraffin sections, respectively. RESULTS: The percentage of p53-expressing cells varied from 3.5 to 90 in BCCs (median value 54.4%) and from 3.7 to 94 in SCCs (median value 40.3%). The mean value of Ki-67-positive cells was comparable in both groups of tumours with a mean value of 40.6% in BCCs and 34.6% in SCCs. Conversely, the TUNEL assay showed sporadic staining of apoptotic cells within the tumours with a mean value of 1.12% in BCCs and 1.8% in SCCs. p53 protein expression was correlated positively with cell proliferation (r = 0.75, P = 0.000001) and negatively with apoptosis (r = -0.23, P = 0.05). CONCLUSION: p53 immunoreactivity was high in the majority of the skin carcinomas examined and correlated positively with cell proliferation and negatively with apoptosis. The p53 protein overexpression appears to be related to an inactivated protein resulting from mutations of the p53 gene or other unclear molecular mechanisms.     

Evidence for small intracellular vesicles in human blood phagocytes containing cytochrome b558 and the adhesion molecule CD11b/CD18

Human neutrophils contain a rapidly mobilizable pool of so-called secretory vesicles distinct from the azurophil granules and specific granules. Using human albumin as a marker for these intracellular vesicles in immuno-electron microscopy, we found that part of the cytochrome b558 in non-purified whole blood neutrophils colocalized in these vesicles. This was detected with monoclonal antibody (MoAb) CLB- 48, binding to the high molecular weight subunit of cytochrome b558. Approximately 65% of the albumin-containing vesicles showed MoAb CLB-48 labeling. This was also found in eosinophilic granulocytes and in monocytes. Cytofluorimetric determination of cytochrome b558 expression on the plasma membrane of intact, nonpurified granulocytes (and monocytes) with MoAb 7D5, which is directed against an extracellular epitope of cytochrome b558, did not show any binding. However, granulocytes (and monocytes) significantly bound 7D5 after density centrifugation. The positive binding of 7D5 to purified neutrophilic granulocytes correlated with a strongly reduced labeling of cytochrome b558 in the albumin-positive vesicles. Binding of CD11b MoAb CLB-B2.12 to the alpha subunit of the complement receptor type 3 (CR3) on the surface of intact, nonpurified neutrophils was detected to a limited extent in whole blood samples, but was strongly increased upon density gradient centrifugation of the cells, as we have described before. Investigation at the ultrastructural level showed that the CD11b antigen codistributed with albumin in vesicular structures in nonpurified phagocytes, especially in neutrophils and eosinophils. Together, these data substantiate the idea of an intracellular store that can be easily mobilized (even under the simple stress condition of density gradient centrifugation). Such mobilization may result in the expression of cytochrome b558 on the plasma membrane, as was indicated in this study. Apart from cytochrome b558, several other surface membrane molecules, as we show here for the integrin CD11b/CD18 (CR3), are probably also located in these rapidly mobilizable intracellular vesicles.     

Pulmonary steal syndrome: an unusual case of coronary-bronchial pulmonary artery communication

The authors report a patient with angina pectoris in whom selective left coronary angiography demonstrated that the pulmonary artery branch to an apical lung segment was supplied by a bronchial collateral vessel which arose from the left circumflex artery. The anatomic and physiological developmental mechanisms, and the clinical implications, are discussed. Relief of the patient's angina following ligation of the pulmonary artery branch indicated the development of a form of pulmonary steal syndrome.