Light-emitting diodes (LED) for domestic lighting: any risks for the eye?

Light-emitting diodes (LEDs) are taking an increasing place in the market of domestic lighting because they produce light with low energy consumption. In the EU, by 2016, no traditional incandescent light sources will be available and LEDs may become the major domestic light sources. Due to specific spectral and energetic characteristics of white LEDs as compared to other domestic light sources, some concerns have been raised regarding their safety for human health and particularly potential harmful risks for the eye. To conduct a health risk assessment on systems using LEDs, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES), a public body reporting to the French Ministers for ecology, for health and for employment, has organized a task group. This group consisted physicists, lighting and metrology specialists, retinal biologist and ophthalmologist who have worked together for a year. Part of this work has comprised the evaluation of group risks of different white LEDs commercialized on the French market, according to the standards and found that some of these lights belonged to the group risk 1 or 2. This paper gives a comprehensive analysis of the potential risks of white LEDs, taking into account pre-clinical knowledge as well as epidemiologic studies and reports the French Agency's recommendations to avoid potential retinal hazards.

Standardized protocols for photocarcinogenesis safety testing

Solar ultraviolet radiation (UVR) is recognized as a major cause of non-melanoma skin cancer in man. Skin cancer occurs most frequently in the most heavily exposed areas and correlates with degree of outdoor exposure. The incidence of skin cancer is also increased by contact with photosensitizing drugs and chemicals such as psoralens, coal tars and petroleum stocks. Other substances which do not act as photosensitizers, such as immunosuppressants taken by organ transplant recipients, also increase the risk of skin cancer. The U.S. Food and Drug Administration requests, on a case-by-case basis, that risk of enhanced photocarcinogenesis is assessed for many classes of drugs. Health Canada's Therapeutic Products Programme has issued a Notice of Intent to regulate pharmaceutical products which may enhance carcinogenicity of the skin induced by ultraviolet radiation. Other national regulatory agencies review such data when they exist, but their own requirements emphasize batteries of short-term in vitro and in vivo tests. While they may support drug development strategies, short-term tests have yet to be validated as predictors of the ability of drugs or chemicals to enhance photocarcinogenesis. Published protocols now describe study designs and procedures capable of determining whether test agents enhance the rate of formation of UVR-induced skin tumors.

Randomised trial of interferon alpha-2a as adjuvant therapy in resected primary melanoma thicker than 1.5 mm without clinically detectable node metastases. French Cooperative Group on Melanoma

BACKGROUND

Owing to the limited efficacy of therapy on melanoma at the stage of distant metastases, a well-tolerated adjuvant therapy is needed for patients with high-risk primary melanoma. Our hypothesis was that an adjuvant treatment with low doses of interferon alpha could be effective in patients with localised melanoma.

METHODS

After resection of a primary cutaneous melanoma thicker than 1.5 mm, patients without clinically detectable node metastases were randomly assigned to receive either 3x10(6) IU interferon alpha-2a, three-times weekly for 18 months, or no treatment. The primary endpoint was the relapse-free interval.

FINDINGS

499 patients were enrolled, of whom 489 were eligible. When used as part of a sequential procedure, interferon alpha-2a was of significant benefit for relapse-free interval (p=0.038). A long-term analysis, after a median follow-up of 5 years, showed a significant extension of relapse-free interval (p=0.035) and a clear trend towards an increase in overall survival (p=0.059) in interferon alpha-2a-treated patients compared with controls. There were 100 relapses and 59 deaths among the 244 interferon alpha-2a-treated patients compared with 119 relapses and 76 deaths among the 245 controls. The estimated 3-year-relapse rates were 32% in the interferon alpha-2a group and 44% in controls; the 3-year death rates were 15% and 21%, respectively. Only 10% of patients experienced WHO grade 3 or 4 adverse events. Treatment was compatible with normal daily life.

INTERPRETATION

Adjuvant therapy of high-risk melanoma with low doses of interferon alpha-2a for 18 months is safe and is beneficial when started before clinically detectable node metastases develop.

Melanoma risk and residence in sunny areas. EORTC Melanoma Co-operative Group. European Organization for Research and Treatment of Cancer

Melanoma risk among subjects from Germany, France and Belgium who had lived for 1 year or more in sunny climates was examined in a one-to-one unmatched case-control study conducted among white subjects 20 years old or more. A total of 412 consecutive patients with melanoma diagnosed from 1 January 1991 onwards, were derived from hospital registers; 445 controls were randomly chosen in the same municipality as the cases. After adjustment for host characteristics, melanoma risk associated with residence in a sunny area was 2.7 (95% CI: 1.4-5.2), increasing to 4.7 (95% CI: 1.4-13.5) if subjects sought a suntan when residing in sunny climates, and to 4.3 (95% CI: 1.7-11.1) if subjects arrived before the age of 10 years in the sunny area. Residence in sunny areas and recreational sun exposure seemed to combine their effects on melanoma risk. Increase in melanoma risk conveyed by deliberate sun exposure during adulthood was highest among subjects who had lived in sunny areas as a child or adolescent and lowest among subjects who had never resided in sunny areas. Our results support conclusions from migrant studies that indicated that childhood is a critical period of either vulnerability to solar radiation or more frequent exposures to melanoma risk factors. They also suggest that moderate sun exposure of an adult who was heavily sun exposed in childhood is associated with a higher melanoma risk than that of high sun exposure of an adult who was sun protected in childhood.

Melanoma and use of sunscreens: an Eortc case-control study in Germany, Belgium and France. The EORTC Melanoma Cooperative Group

Use of sunscreens is widely advocated as a preventive measure against sun-induced skin cancers. However, to date, no epidemiologic study has reported a decreased melanoma risk associated with sunscreen use. We have conducted a case-control study aimed at evaluating the influence of sunscreen use on the occurrence of cutaneous malignant melanoma. In 1991 and 1992, 418 melanoma cases and 438 healthy controls were interviewed in Germany, France and Belgium. The questionnaire used differentiated between regular sunscreens, psoralen sunscreen (prepared with 5-methoxypsoralen, a tanning activator and photocarcinogen), and self-tanning cosmetics (which produce a tan without ultraviolet radiation). After adjusting for age, sex, hair colour and holiday weeks spent each year in sunny resorts, the melanoma risk was of 1.50 (95% Cl:1.09-2.06) for regular sunscreens, and of 2.28 (95% Cl: 1.28-4.04) for psoralen sunscreens. No melanoma risk was associated with use of self-tanning cosmetics. Among subjects with a poor ability to tan, psoralen sunscreen users displayed a melanoma risk of 4.45 (95% Cl: 1.25-15.8) when compared with regular sunscreen users. There was a significant negative interaction between regular sunscreen use and sunburns experienced in adulthood. Use of sunscreens, especially psoralen sunscreen, was associated with higher density of pigmented lesions of the skin. Although we cannot exclude the presence of an unknown confounding factor, our results support the hypothesis that sunscreens do not protect against melanoma, probably because of their ability to delay or avoid sunburn episodes, which may allow prolonged exposure to unfiltered ultraviolet radiation. Serious doubts are raised regarding the safety of sunscreens containing psoralens.

Cutaneous malignant melanoma and exposure to sunlamps or sunbeds: an EORTC multicenter case-control study in Belgium, France and Germany. EORTC Melanoma Cooperative Group

The study objective was to assess whether exposure to sunlamps and sunbeds represents a risk factor for cutaneous malignant melanoma (CMM). A 1-to-1 unmatched case-control study was conducted among subjects 20 years old or more with naturally non-pigmented skin in Germany, France and Belgium. A total of 420 consecutive patients with CMM diagnosed from 1 January 1991 onward were derived from hospital registers; 447 controls with no history of skin cancer were chosen at random in the same municipality as the cases. Exposure to sunlamps or sunbeds starting before 1980 is associated with a crude estimated risk of CMM of 2.71 (95% CI: 1.06-7.78) for at least 10 hr of accumulated exposure. This risk is of 2.12 (95% CI: 0.84-5.37) after adjustment for age, sex, hair colour and average number of holiday weeks each year in sunny resorts. Subjects who experienced skin-burn due to sunlamps or sunbeds, and who had accumulated at least 10 hr of exposure, displayed a crude estimated CMM risk of 4.47 (95% CI: 1.45-13.7), which rose to 8.97 (95% CI: 2.10-38.6) for those who exposed their skin for tanning purposes. The risk associated with skin-burn is only marginally modified after multiple adjustments for host characteristics and recreational exposure to sunlight. Apparently, sunlamps and sunbeds share the increased risk of CMM, which seems to concentrate in subjects exhibiting hazardous behaviour towards ultraviolet radiation sources. However, although it is reasonable to believe that high doses of pure ultraviolet A radiation can be dangerous, this is not firmly established by this study. Most exposures to ultraviolet A tanning devices began after 1980; therefore, epidemiologic studies have difficulty in revealing any increase in risk of CMM starting after 1980 because of the latent period between exposure and occurrence of melanoma. Public health authorities should have a cautious approach towards the rapidly developing fashion of tanning under sunlamps or sunbeds.

Recreational exposure to sunlight and lack of information as risk factors for cutaneous malignant melanoma. Results of an European Organization for Research and Treatment of Cancer (EORTC) case-control study in Belgium, France and Germany. The EORTC Malignant Melanoma Cooperative Group

This study addressed the impact of exposure to ultraviolet radiation on the risk of cutaneous malignant melanoma (CMM), as well as the behavioral components at stake in its occurrence. We performed a one-to-one unmatched case-control study among subjects aged 20 years or more with naturally non-pigmented skin in Germany, France and Belgium. Four-hundred and twenty consecutive patients with CMM diagnosed from 1 January 1991 on were derived from hospital registries; 447 controls were chosen randomly in the same municipality as cases. Subjects unaware of the dangers of exaggerated exposure to sunlight display an estimated CMM risk of 3.72% (95% confidence interval 2.63-5.26). The number of holiday weeks spent annually in sunny resorts and sunbathing during the hot hours of the day are strong risk factors in the three countries, but not the number of years spent outdoors, as farmers or building workers. Multiple logistic adjustments on the host characteristics increases the CMM risk associated with recreational exposure to sunlight, as well as the adjustment on the unawareness of the dangers of exaggerated exposure to sunlight. Recreational exposure to sunlight and sunburn early in life seem capable of fostering the proliferation of pigmented lesions of the skin. Our data support the hypothesis that most CMM develop from pigmented lesions of the skin containing initiated melanocytes, and that the cell proliferation due to brutal, intermittent exposures to solar radiation amplifies the likelihood of a melanocyte entering into a malignant process.(ABSTRACT TRUNCATED AT 250 WORDS)

Validity of the histopathological criteria used for diagnosing dysplastic naevi. An interobserver study by the pathology subgroup of the EORTC Malignant Melanoma Cooperative Group

Ten (dermato)pathologists studied 50 cutaneous melanocytic lesions including common naevocellular naevi, dysplastic naevi (DN), melanomas in situ and invasive primary melanomas, with emphasis on the histological criteria of DN. Using a standardised form, 20 defined histopathological features were scored (semi)quantitatively. Concordance of diagnosis, efficacy and reproducibility of features were investigated. DN were distinguished well from the other entities (mean Po 0.87). Agreement on the degree of atypia of DN was low. The reproducibility of the scoring was best for the following features: irregular nests, lymphohistiocytic infiltrate, marked junctional proliferation and large nuclei. The overall values of these features to discriminate between DN and non-DN were better than for the other features studied. Using the presence of at least three of the four features as a condition for the diagnosis of DN, values for sensitivity, specificity and positive and negative predictive values were 0.86, 0.91, 0.96 and 0.73, respectively. On the basis of the results these features seem best suited as histological criteria for the diagnosis of DN.

[Biological effects of solar radiations]

Main biological effects of ultra-violet radiations are discussed. At a dermatological point of view, most of these effects are harmful: actinic erythema, cutaneous cancerogenesis (basal and spinous cell carcinomas, malignant cutaneous melanomas). Photo-immunosuppression and photoaging of the skin are discussed. Two benefic actions of sunlight are reviewed: synthesis of vitamin D3 and positive action of visible radiations on human psychism.

Erythema induced by quartz-halogen sources

The erythemal effect of 100-W quartz-halogen sources, previously predicted from radiation measurements, was directly measured on humans at a distance of 10 cm. Minimal erythema was produced in 15 min for skin type I. These data show that normal use of a desktop lamp should not usually lead to erythema in one day, but that long-term effects cannot be ignored, because for lifetime use at work, the relative risk for squamous cell carcinoma on the back of the hands is 3.4.

Photo-induced events in the human melanocytic system: photoaggression and photoprotection

The human skin is submitted to solar, essentially ultraviolet radiation (UVR), aggressions, and develops, for sufficient doses, erythema and pigmentation. The individual sun-sensitivity depends on the nature and the quantity of melanins present in the epidermis. These parameters are inherited as genetic traits which account for the large variations of the constitutive and adaptive pigmentation encountered in the caucasian populations. From red-haired skin-sensitive individuals, to dark-haired sun-resistant individuals, phaeomelanins (red) and eumelanins (black) are mixed in variable proportions. Pure melanins extracted from red hairs and black hairs behave differently when submitted to ultraviolet radiations: phaeomelanins develop aggressive species of molecules responsible for DNA damages, mutations, and cell death. On the contrary, eumelanins are less toxic for the major cellular metabolisms. The sun-sensitive populations suffer from more skin cancer of all types than the dark ones. In particular, they are exposed significantly to higher risk of melanoma and to the risk of bearing more nevi following large solar exposures early in the life.

A linkage study between HLA and cutaneous malignant melanoma or precursor lesions or both

In seven pedigrees displaying the familial atypical multiple mole-melanoma (FAMMM) syndrome, three successive linkage analyses were performed between HLA and an assumed dominant gene determining respectively each of the following affected phenotypes: (1) precursor lesions, (2) cutaneous malignant melanoma (CMM), and (3) precursor lesions or CMM or both. Close linkage could be excluded in (1) and (3). However, if the transmission of malignant melanoma itself were assumed to be due to a single gene different from the one responsible for precursor lesions, a maximum lod score of 1.64 was observed at a recombination fraction of 5%, assuming low penetrance values. These different results are discussed in respect to the possible mechanisms causing the familial distribution of these traits. Two alternative hypotheses were proposed. Either the FAMMM syndrome is a rare genetic entity not closely linked to HLA or the association and transmission of precursor lesions and CMM in families are due to several factors among which HLA might play a role.

Antimelanoma hybridoma antibodies against partially purified melanoma antigen

We have immunised BALB/c mice with a melanoma antigen obtained after papain solubilisation of the membranes of a metastatic melanoma tumour and fused the immune spleen cells to the mouse myeloma line P3-NS1/1-Ag4.1. The produced hybridoma antibodies (Mel-PV antibodies) recognised the initial melanoma antigen in haemagglutination, but did not react with any of the HLA phenotypes tested by cytotoxicity on a panel of B lymphocytes with known HLA-A and B phenotypes. We rosetted red blood cells coated with protein A with dispersed cells from fresh melanoma tumours, and a high degree of specificity for human malignant melanocytes was observed. Purified Mel-PV antibodies were also tested by indirect immunofluorescence and found to be oriented towards cytoplasmic components of malignant melanoma cells. These results indicate that the use of melanoma antigens for preparing monoclonal antibodies maintained a satisfactory degree of specificity and may be an adequate starting point for defining common and specific antigenic determinants on human melanoma.

Preclinical and clinical evaluation of topical acid products for skin tumors

Distinct differences between topical acid preparations can be detected by simple preclinical and clinical pharmacologic models designed to evaluate potential utility in the treatment of superficial skin tumors. The models distinguish a tissue-dissolving (ulcerating) effect from a tissue-fixation (mummifying) effect, as reflected by a distinct and lasting discoloration of hair in vitro or the skin surface in vivo. Double-blind clinical comparison of the response to different preparations of matched pairs of small superficial skin tumors in 33 subjects demonstrated for greater utility for nitric acid preparations of appropriate strength (6 to 7N), with added oxidizable organic acids, over the mineral acid alone. The nitrate reduction products generated in such preparations markedly speed up discoloration in the models and apparently contribute to the improved clinical utility of the topical treatment by enhancing the speed and intensity of tissue fixation, but not tissue erosion. The architecture of lesions eradicated by such mixtures is generally adequately preserved for histologic diagnosis of the extruded tissue.

[Augmentation of HL-A A9 antigen in malignant melanoma, principally in metastatic or recurrent forms. Apropos of 105 cases of melanoma of which 34 were serious forms]

HLA-A and B phenotypes of 105 patients suffering from malignant melanomas were determined, with special regard for metastatic form or relapse. A highly significant increase of the HLA-A9 antigen is seen (X2 = 17.47); such data had already been shown by van Wijek [2], but other authors did not find this abnormality when studying melanomas whose histologic form was not specified.

Difficulties encountered in the application of Clark classification and the Breslow thickness measurement in cutaneous malignant melanoma

The purpose of this study was to analyse the reproducibility of Clark's classification and Breslow's measure of tumor thickness to determine if there is general agreement among pathologists regarding these parameters and whether these pathologists reach consistent conclusions concerning each slide. Three successive workshops including a panel of pathologists were held at Amsterdam, in May 1977; at Villejuif in June 1977, followed by circulation of slides and at Villejuif again, in June 1978, followed by slide projection. This was necessary because of the great divergencies of opinion noted at the first meeting at Amsterdam. These sessions gave a better understanding of the divergencies and finally indicated that general agreement could only be reached by slide presentation followed by discussion. Regarding histogenesis, agreement between pathologists was improved after discussion from 6/11 cases to 11/13 cases. Regarding the level, no initial agreement was reached (Amsterdam). At the second meeting an agreement was obtained in 4/13 cases and finally in 11/13 cases (Villejuif). Clark's classification is more difficult to use than Breslow's because it depends on a discontinuous variable, the choice of the infiltration level. Breslow's classification, on the other hand, is based on a continuous variable. Because of frequent discrepancies, the classification of patients into various therapeutic groups according to Clark's level and Breslow's thickness necessitates that all cases including in therapeutic trials be reviewed by a panel of pathologists.

Immunoelectron microscopy of type III collagen in normal and scleroderma skin

Normal and scleroderma skin was studied by indirect immuno-electron microscopy with specific antibodies against Type III collagen. Fine collagen fibrils, 200-400 A in diameter were labeled with antitype III collagen antibodies. These antibodies attached to the collagen fibril forming rings with a 650 A periodicity. Fibrils with more than 600 A in diameter were only labeled with antitype I collagen antibodies. Type III collagen was found around small blood vessels, adipocytes and smooth muscle cells, thus, corresponding to the distribution of reticulin.

[Skin lesions revealing a glucagonoma (author's transl)]

About a case of necrolytic migratory erythema erythema revealing a malignant pancreatic glucagonoma, the authors compare the results of their study with the 25 cases published in the world.

Human peripheral Nullymphocytes: ultrastructural aspects of the "K" cell effect against a melanoma target cell

A null cell fraction was isolated from human peripheral blood by Ficoll density gradient centrifugation followed by removal of mononuclear phagocytes, passage through Ig-antiIg columns and sedimentation of E-rosette forming T cells. In contrast to the T cell fraction in the Null cell population exhibited cytotoxic activity against antibody-sensitized human melanoma target cells (ADCC reaction). This activity could be attributed to a low affinity Fc-receptor bearing cells present in the Null cell preparation. At the ultrastructural level in 2 h ADCC reaction most tumor cells were surrounded by up to 10 lymphoid cells which showed narrow junctions with parallel plasma membranes and local evaginations of lymphoid cells into recessus of the target melanoma cells. The mononuclear cell type found in close contact with the antibody-sensitized target cells had the following morphological criteria: 8 to 10 mu diameter, irregular nucleus, discrete rough endoplasmic reticulum, isolated ribosomes, cytoplasmic organelles concentrated under a ruffling membrane in the contact area with the tumor cell.

[Urinary evaluation of 5-S-cysteinyldopa and seric evaluation of IgG4 subclass during follow-up of 27 primitive malignant melanomas (author's transl)]

27 patients with SSM or NM level IV and V have been submitted to a monthly evaluation of their level of 5-S-cysteinyldopa in the urine and IgG4 subclass in their sera. For 5 patients who entered the stage II of their disease during the follow-up, 3 had elevation of the 5S and 5 had large variations of IgG4. On 21 patients in clinical remission, 10 had conjunctly an increase of 5S and variations of IgG4. The predictional value of these tests is discussed.

[Melanocytes in epiloia; ultrastructural aspects (about 7 cases) (author's transl)]

Hypopigmented macules of epiloia have been studied by photonic and electron microscopy in 7 cases. The number of melanocytes was not decreased but these cells were hypotrophic and had a low tyrosinae activity. The melanosomes were smaller in size and their maturation rate was greatly reduced; many abnormal round and granular melanosomes, phaeomelanosome-like, were observed. In one case, such abnormal melanocytes were also occasionally found in normally pigmented control skin.

[Replication of immune RNA by human lymphoblastoid cells]

Animal immune RNA used for the induction of the human lymphoblastoid cell line LDV/7, induces the appearance of receptor sites on the surface of these cells and the synthesis of specific immunoglobulins which are liberated into the culture medium. Furthermore, RNA has been extracted from these cells, which possesses the same properties of specific cytotoxicity as the RNA used for induction. It is supposed that the immune RNA derepresses specific genes on the genome of the induced cells.

[IgG levels in the sera of melanoma patients (author's transl)]

397 sera from 185 melanoma patients have been tested. We classified our subjects into three groups, according to the stage of disease. An alteration of the level of IgG4 subclass was found and related to the extension of the disease. The percentage of abnormalities was more frequent in stage II and III (55 p. 100 and 53 p. 100) than in stage I (19 p. 100). High titers of IgG 4 subclass were essentially detected in advanced disease. The biological significance is discussed.

[IgG levels in the sera of melanoma patients (author's transl)]

397 sera from 185 melanoma patients have been tested. We classified our subjects into three groups, according to the stage of disease. An alteration of the level of IgG 4 sub-class was found and related to the extension of the disease. The percentage of abnormalities was more frequent in stage II and III (55 p. 100 and 53 p. 100) than in stage I (19 p. 100). High titers of IgG 4 subclass were essentially detected in advanced disease. The biological significance is discussed.

IgG4 subclass in malignant melanoma

Three hundred and ninety-seven sera from 185 melanoma patients were studied. These sera were classified into three groups according to stage of disease. An alteration in the level of the IgG4 subclass was found. It was related to the dissemination of disease. The percentage of abnormalities (either increased or decreased levels of IgG4) was more frequent in patients with stage II and III diseases (55 and 53%, respectively) than in patients with stage I(19%). The higher frequencies of high titers of IgG4 were essentially detected in advanced disease. The biologic significance of the increase of IgG4 in melanoma remains obscure. The increase may be related to the development of facilitating antibodies of the IgG4 subclass.

[IgG subclasses in malignant melanoma]

The 397 sera from 185 melanoma patients have been studied and classified in three groups according to the stage of disease. Our findings revealed an alteration of the level of IgG4 subclass which is related to the dissemination of disease. The percentage of abnormalities (either increased or decreased levels of IgG4) was more frequent in stage II and III (55% and 53% respectively) than in stage I (19%), The higher frequencies of high titers of IgG4 were essentially detected in advanced disease. The biological significance of the increase of IgG4 in melanoma remains obscure. It may be related to the development of facilitating antibodies of IgG4 subclass.

Ultrastructure and virus particles of L1210/Mes. A hamster-adapted murine leukemia

The ultrastructural features and virus particle content of L1210/Mes., the hamster-adapted strain of murine leukemia L1210, has been studied in cheek pouch tumors and cell cultures. In comparison with the parental murine tumor in culture, L1210/Mes. has experienced certain morphologic alterations, such as a striking increase in cell size, enlarged and more bizarre nuclei, and an increase in the number of lysosome-related structures. Type A (intracytoplasmic and intracisternal) and type C virus particles could be demonstrated in cell cultures of murine leukemia L1210, and in cheek pouch grafts and cell cultures of L1210/Mes. No. "H" (or "R") hamster-associated virus particles, however, could be distinguished in L1210/Mes. tumors or in vitro cultivated cells. It appears that a murine lymphoma capable of serial propagation in a xenogeneic host permits the replication of virus particles structurally indistinguishable from those indigenous to it.

Cell-mediate cytotoxicity in vitro of human lymphocytes against a tissue culture melanoma cell line (igr3)

Purified peripheral blood lymphocytes from 13 healthy donors, 6 melanoma patients and 1 halo nevus patient were tested for cytotoxic activity against an allogeneic melanoma cell line (IGR3) in, at least, one of the following assays: cell-mediated cytotoxicity (ADCC) and microcytotoxicity assays (ma). The lymphocytes were isolated by Ficoll-Triosil gradient centrifugation (fraction F) followed by removal of iron-phagocytosing and adherent cells (fraction FFF) and by subsequent passage through anti-IgG columns (fraction FFF-C). Leukocytes of each fraction were identified by different methods including morphology, rosette-formation, phagocytic activity, and membrane fluorescence. CMC activity paralled ADCC activity at a log lower level of sensitivity. In both assays lymphocytes of fractions F and FFF had the highest activity, whereas in fraction FFF-C cytotoxicity was strongly reduced. In all three lymphocyte fractions CMC and ADCC activity could be blocked by preincubation of the effector cells in aggregated IgG. Furthermore, depletion of E rosette-forming lymphocytes slightly increased ADCC and CMC activity, whereas depletion of EA and EAC rosette-forming lymphocytes strongly decreased it. Our results therefore indicate that in both CMC and ADCC assays, non-adherent, non-phagocytic Fc receptor-bearing lymphocytes ("K" cells) were the active cytotoxic cells. In MA, on the other hand, mononuclear phagocytes seemed to be the most active cell population. So far no significant difference was observed in CMC, ADCC, and MA between control persons and melanoma patients

Cell-Mediated Cytotoxicity in Vitro of Human Lymphocytes against a Tissue Culture Melanoma Cell Line (IGR3)

Purified peripheral blood lymphocytes from 13 healthy donors, 6 melanoma patients and 1 halo nevus patient were tested for cytotoxic activity against an allogeneic melanoma cell line (IGR3) in, at least, one of the following assays: cell-mediated cytotoxicity (CMC), antibody-dependent cellular cytotoxicity (ADCC) and microcytotoxicity assays (MA). The lymphocytes were isolated by Ficoll-Triosil gradient centrifugation (fraction F) followed by removal of iron-phagocytosing and adherent cells (fraction FFF) and by subsequent passage through anti-IgG columns (fraction FFF-C). Leukocytes of each fraction were identified by different methods including morphology, rosetteformation, phagocytic activity, and membrane fluorescence.

CMC activity paralled ADCC activity at a log lower level of sensitivity. In both assays lymphocytes of fractions F and FFF had the highest activity, whereas in fraction FFF-C cytotoxicity was strongly reduced. In all three lymphocyte fractions CMC and ADCC activity could be blocked by preincubation of the effector cells in aggregated IgG. Furthermore, depletion of E rosette-forming lymphocytes slightly increased ADCC and CMC activity, whereas depletion of EA and EAC rosette-forming lymphocytes strongly decreased it. Our results therefore indicate that in both CMC and ADCC assays, non-adherent, non-phagocytic Fc receptor-bearing lymphocytes (“K” cells) were the active cytotoxic cells. In MA, on the other hand, mononuclear phagocytes seemed to be the most active cell population. So far no significant difference was observed in CMC, ADCC, and MA between control persons and melanoma patients.

Branched tubular structures in human malignant melanoma

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