Evaluation of the sentinel node is a useful procedure to identify patients to be submitted for complete lymph node dissection. The procedure makes it possible to assess the best prognosis of patients.
Reflectance spectrophotometry from 420 to 780 nm on 31 primary melanoma and 31 benign nevi has been performed by using an external integrating sphere coupled to a spectrophotometer. Measurements show that reflectance spectra of melanoma and nevi manifest dissimilar patterns. From these spectra four variables, whose physical and/or physiological meanings remain to be investigated, have been derived. All of them are significantly different when compared between melanoma and nevi. A discriminant function between the two groups of lesions has been determined by using a stepwise discriminant analysis, resulting in a test with a sensitivity of 90.3% and a specificity of 77.4%. This method of discrimination between melanoma and nevi seems to have a discriminating power almost equal to that of a clinical judgement from a specialized medical doctor, thus suggesting a new method for screening skin pigmented lesions.
The frequencies of cytotoxic T-lymphocyte precursors (CTLp) that lyse autologous tumor by a T-cell receptor (TCR)-dependent mechanism (specific CTLp) were evaluated by limiting dilution analysis (LDA) using lymphocytes from peripheral blood (PBL) and from surgically resected, tumor-invaded lymph nodes (LNL) in 9 melanoma patients. The frequency of specific CTLp was determined in PBLs and/or LNIs of all patients by a modified LDA assay, enabling us to measure lytic activity on the autologous tumor that could be significantly inhibited by an anti-CD3 monoclonal antibody (MAb). This assay allowed us to detect frequencies of specific CTLp ranging from 1/720 to 1/32,037 in peripheral blood and from 1/328 to 1/22,061 in tumor-invaded lymph nodes. These frequencies indicated that lymphoid populations from PBLs or LNLs of melanoma patients may contain as low as 30 to as much as 3,000 specific CTLp/10(6) lymphocytes. In addition, comparison of wells containing specific CTLp with those showing no inhibition by anti-CD3 MAb indicated that specific CTLp represent between 3 and 88% of all precursors with lytic activity on the tumor. In 6 of 9 patients, no marked differences between PBLs and LNIs in specific CTLp frequencies were found. A 10-fold increase of specific CTLp, in comparison to PBL and LNL, was found only in lymphocytes isolated from a subcutaneous metastasis of one patient. Our results indicate that CTLp interacting with autologous tumor by a TCR-dependent mechanism exist in PBL and LNL of most melanoma patients, although a wide variation in their absolute number is evident among different patients.
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