Immunology and growth characteristics of ocular basal cell carcinoma.

BACKGROUND: Knowledge about immunological features and growth characteristics of palpebral (ocular) basal cell carcinomas (BCCs) is limited. In particular, it is unclear whether ocular BCC represents in this regard a special BCC entity or not. METHODS: Twenty BCCs of the lid area (ocular BCCs) were investigated immunohistologically using monoclonal antibodies against CD4, CD8, CD45Ro, CD50, CD68, HECA-452, Ki67 (MIB1), and the p53 epitope. For comparison, nine BCCs excised distant from the eye (non-ocular BCCs) were evaluated. RESULTS: In BCCs the distribution of the immunocompetent cells investigated is markedly irregular. These cells are localized mainly around BCC islands. Only a few of them invade tumour cell aggregates. The CD4:CD8 ratio as detected by immunohistochemistry is >1 in 82% of ocular BCCs and in 88% of nonocular BCCs. Often there are dense infiltrations of CD68+ cells (macrophages) and HECA-452+ cells adjacent to tumour cell aggregates. The growth fraction [percentage of proliferating (Ki67+/MIB 1+) cells] varies from 0% to more than 30%. Proliferative activity is enhanced at the invasion front. Additionally, the amount of p53+ cells differs considerably among the BCCs. CONCLUSIONS: CD4+ T cells seem to be the most important cell population for BCC immunosurveillance, offering the chance for conservative interferon therapy. The role of CD68+ and HECA-452+ cells has to be further elucidated. In many tumours the large amount of proliferating cells contrasts to the usually slow growth of BCCs, indicating strong apoptotic processes. The results can be regarded only as semiquantitative. So far, ocular and nonocular BCCs exhibit no essential differences regarding immunocompetent cell infiltration and growth characteristics. According to this, palpebral BCCs are "normal" BCCs and not a special BCC variant. Therefore, results from dermatological research concerning BCC can be extended without limitations to their counterparts in the lid area.

[Telomerase activity in uveal melanomas]. / Telomeraseaktivität in uvealen Melanomen.

BACKGROUND: The maximum number of cell divisions of a certain cell population is genetically fixed so that aging cells become non-dividing (senescent) at least. This replicative life span, also known as "Hayflick limit", is probably defined by a "critical" length of the telomeres. Telomeres are special DNA-sequences located at the four ends of the chromosomes which are shortened with each cell cycle. Cells of most, but not all malignant tumours have been shown to reactivate the enzyme telomerase so that telomeres can be reconstructed, "Hayflick limit" can be overcome, and unlimited cell division can be established. This study was undertaken to elucidate whether telomerase reactivation is used by uveal melanoma cells. MATERIALS AND METHODS: Fresh tumour tissue was removed from 10 untreated uveal melanomas after enucleation. Telomerase activity was determined using a PCR ELISA according to the Telomeric Repeat Amplification Protocol (TRAP). Normal tissue of the skin and the conjunctiva served as control. RESULT: Telomerase activity was detectable in 90% of the investigated uveal melanomas. All control specimens were telomerase negative. CONCLUSIONS: Uveal melanoma growth seems to depend on telomerase reactivation. Thus, telomerase inhibition could offer a new principle for uveal melanoma therapy in the future.

Ophthalmomyiasis externa due to the sheep botfly Oestrus ovis (Diptera: Oestridae) in southwest Germany.

We present a case of ophthalmomyiasis externa in a 54-year-old man in southwest Germany (Baden-Württemberg). After the patient had been attacked by a fly, he complained of a foreign-body sensation and itching in his right eye and developed purulent conjunctivitis. Slit-lamp examination revealed the presence of translucent, rapidly moving insect larvae in the conjunctival sac and on the corneal surface. Following removal of all larvae and instillation of gentamicin, the symptoms completely resolved within 2 days. Two of the nine larvae removed were examined by light microscopy and taxonomically classified as first-instar larvae of the sheep botfly Oestrus ovis L. 1758. Although this fly is the most common causative agent of external ophthalmomyiasis in the world, infestations in central Europe have only rarely been reported. Besides the case report and a detailed description of the larvae, an overview of the literature on European cases of ophthalmomyiasis externa caused by Oestrus ovis is given.

Premetastatic uveal melanoma cells do not express laminin receptors.

Interactions between extracellular matrix and tumor cells are of great importance for tumor cell invasion. They are mediated by cellular surface receptors (integrins). As the glycoprotein laminin enhances invasion in some neoplasms and as the expression of laminin receptors is sometimes correlated with the invasive activity, the tumor cell-laminin receptor-laminin cascade could play a key role in melanoma cell spread as well. We therefore investigated 12 uveal melanomas with a monoclonal anti-laminin-receptor antibody. In all, 9 tumors demonstrated no reaction and 3 exhibited just a partial and slight reaction. Endothelial cells within the melanomas were laminin-receptor-positive. As laminin is found primarily in basement membranes, laminin receptors are expressed mainly by cells in contact with these structures, e.g., endothelial, epithelial, and carcinoma cells. The nonepithelial uveal melanomas, which produce only little basement membrane material, if any, seem to have no need for laminin receptors, at least provided that basement membranes do not have to be traversed. As a result, laminin receptors are not expressed.