Interferon-gamma regulates the T cell response to precursor nevi and biologically early melanoma

To examine the potential regulatory role of interferon-gamma in the cellular immune response to melanoma and its precursor lesions, we have tested the capacity of this lymphokine to enhance HLA class II antigen-dependent T lymphocyte blastogenesis, its in vitro production by autologous T cells stimulated by melanoma, and its presence in melanocytic lesions in situ. Cell lines derived from a dysplastic nevus, a radial growth phase primary tumor, a vertical growth phase primary, and metastatic lesions were induced by recombinant interferon-gamma to express increased amounts of HLA class II antigens. Such cells were then examined in radioimmunoassay for expression of HLA-DR antigens and in co-culture for their ability to stimulate proliferation of autologous T cells. Interferon-gamma treatment of melanocytic cells increased their expression of HLA-DR antigens threefold to sixfold. In parallel with these findings, co-culture of T cells with interferon-treated cells of a dysplastic nevus and a radial phase melanoma led to augmented T cell incorporation of tritiated thymidine, and this stimulation was inhibited with a monoclonal antibody to HLA-DR antigens. Despite augmented expression of HLA class II antigens (HLA-DR, -DQ, and -DP), vertical growth phase and metastatic melanoma cells failed to stimulate autologous T cells. When T cells were co-cultured with stimulating melanoma cells, culture supernatants contained significantly increased amounts of interferon-gamma (12 U/ml) in comparison with supernatants of T cells alone (4 U/ml). No interferon was detectable in cultures of melanoma cells alone. To link these in vitro phenomena to in situ events, we used murine monoclonal antibodies to interferon-gamma, the interleukin 2 receptor, and HLA-DR antigens in an immunoperoxidase system to detect interferon production and lymphocyte activation in frozen sections of lesions representative of melanocytic tumor progression. In these studies, precursor dysplastic nevi and radial phase melanomas contained the highest numbers of activated lymphocytes and stained positively for interferon-gamma. These results suggest that interferon-gamma plays a central role in the regulation of the cellular immune response to melanoma. It is produced by T cells, likely activated by tumor antigens seen in the context of HLA class II antigens. In turn, interferon-gamma production enhances expression of HLA class II antigens by melanoma and precursor cells, and such enhancement is associated with additional T cell activation in a positive feed-back loop.

Interferon-gamma regulates the T cell response to precursor nevi and biologically early melanoma

To examine the potential regulatory role of interferon-gamma in the cellular immune response to melanoma and its precursor lesions, we have tested the capacity of this lymphokine to enhance HLA class II antigen-dependent T lymphocyte blastogenesis, its in vitro production by autologous T cells stimulated by melanoma, and its presence in melanocytic lesions in situ. Cell lines derived from a dysplastic nevus, a radial growth phase primary tumor, a vertical growth phase primary, and metastatic lesions were induced by recombinant interferon-gamma to express increased amounts of HLA class II antigens. Such cells were then examined in radioimmunoassay for expression of HLA-DR antigens and in co-culture for their ability to stimulate proliferation of autologous T cells. Interferon-gamma treatment of melanocytic cells increased their expression of HLA-DR antigens threefold to sixfold. In parallel with these findings, co-culture of T cells with interferon-treated cells of a dysplastic nevus and a radial phase melanoma led to augmented T cell incorporation of tritiated thymidine, and this stimulation was inhibited with a monoclonal antibody to HLA-DR antigens. Despite augmented expression of HLA class II antigens (HLA-DR, -DQ, and -DP), vertical growth phase and metastatic melanoma cells failed to stimulate autologous T cells. When T cells were co-cultured with stimulating melanoma cells, culture supernatants contained significantly increased amounts of interferon-gamma (12 U/ml) in comparison with supernatants of T cells alone (4 U/ml). No interferon was detectable in cultures of melanoma cells alone. To link these in vitro phenomena to in situ events, we used murine monoclonal antibodies to interferon-gamma, the interleukin 2 receptor, and HLA-DR antigens in an immunoperoxidase system to detect interferon production and lymphocyte activation in frozen sections of lesions representative of melanocytic tumor progression. In these studies, precursor dysplastic nevi and radial phase melanomas contained the highest numbers of activated lymphocytes and stained positively for interferon-gamma. These results suggest that interferon-gamma plays a central role in the regulation of the cellular immune response to melanoma. It is produced by T cells, likely activated by tumor antigens seen in the context of HLA class II antigens. In turn, interferon-gamma production enhances expression of HLA class II antigens by melanoma and precursor cells, and such enhancement is associated with additional T cell activation in a positive feed-back loop.

Hereditary melanoma and the dysplastic nevus syndrome: the risk of cancers other than melanoma

We analyzed the prospective occurrence of cancers other than malignant melanoma in fourteen kindreds with hereditary cutaneous malignant melanoma and the dysplastic nevus syndrome. No significant excess of nonmelanoma cancers was documented, suggesting that hereditary cutaneous malignant melanoma/dysplastic nevus syndrome is not pleiotropic for other tumor types.

Natural killer cells in the host response to melanoma

Using an immunoperoxidase technique, we have investigated natural killer (NK) cells in the host response to malignant melanomas and melanocytic nevi in frozen sections. Eight primary melanomas, 12 metastatic melanomas, and 31 dysplastic nevi were studied. NK cells were identified phenotypically using an antibody, B73.1, against an Fc receptor present only on NK cells and neutrophils. Rare NK cells were identified in three of 31 dysplastic nevi and in one of eight melanomas. In contrast, significant numbers of NK cells were identified in ten of 12 metastases.

Monoclonal antibody-defined correlations in melanoma between levels of GD2 and GD3 antigens and antibody-mediated cytotoxicity

A monoclonal antibody is described that specifically detects the ganglioside antigens GD2 and GD3, binding preferentially to GD2, in melanoma. Antibody specificity was demonstrated with solid-phase radioimmunoassay and enzyme-linked immunosorbent assay as well as by immunostaining on thin-layer chromatography plates using structurally characterized gangliosides. Binding of both the IgG3 antibody and its IgG2a switch variant were assayed on live cells by cytofluorography and by immunoperoxidase staining on frozen tissue sections. The binding patterns correlated with antitumor activity in antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity assays with human effector cells and complement in an 111In-release assay using cell lines derived from the same individual. The significant level of killing in all tumor cells tested that express GD2, GD3, or both, suggests the importance of multiple specificity towards tumor antigens, i.e., binding of a monoclonal antibody to two or more tumor-associated antigens.

GD2 ganglioside biosynthesis is a distinct biochemical event in human melanoma tumor progression

Gangliosides from cell cultures established from melanocytic lesions, representing different stages of melanoma tumor progression, were analyzed by chemical and immunological means on thin-layer chromatograms. The GD2 ganglioside and N-acetylgalactosaminyl transferase, which catalyzes the biosynthesis of GD2 from its precursor GD3, were detected in cultures established from advanced primary and metastatic melanomas, but not in cultures of normal melanocytes. Immunohistochemical studies on tissue sections from all progression stages confirmed GD2 expression only in these advanced lesions. A distinct biochemical event thus coincides with the onset of faster growth and acquisition of metastatic competence in human melanoma tumor progression.

The dysplastic naevus syndrome in patients with cutaneous malignant melanoma in Western Australia

One hundred and three patients with cutaneous malignant melanoma responded to an invitation to attend a dermatology outpatient clinic. All patients with a family history of melanoma, a history of multiple melanomas, or histological evidence of a dysplastic naevus that was associated with their melanoma were invited. A random sample of other patients with cutaneous malignant melanoma was also invited to attend. First-degree relatives of patients with the dysplastic naevus syndrome (DNS) were invited for a similar examination. DNS was found in 27% of the patients with a family history of melanoma, multiple melanomas, or histological evidence of a dysplastic naevus in association with their melanoma, and in 6% of the remaining patients who were selected at random. DNS was estimated to be present in 12.8% of 17- to 55-year-old patients with cutaneous malignant melanoma in the Perth region, while familial DNS was present in 4.5%. Patients with melanomas with DNS were more likely to be young men and to have numerous naevi, particularly on the lateral surfaces of the arms, shoulders and trunk, than were patients with melanomas without the syndrome.

Human cutaneous nevi transplanted onto nude mice: a model for the study of the lesional steps in tumor progression

Normal human cutaneous nevi were transplanted to the skin of nude mice and some of the grafts were treated topically with 7,12-dimethylbenz[a]anthracene (DMBA, 1.6 mumol weekly). Histologically proven human skin was present in 22 grafts. In the 9 untreated control grafts, the tendency of nevic cells to form nests and the number of nevomelanocytes decreased with time; the melanocytic cells showed no signs of hypertrophy or atypia. In most of the 14 specimens treated with DMBA, the nevomelanocytes showed distinct signs of hypertrophy. The cells were enlarged and often dendritic and were filled with melanin granules for which the transfer to keratinocytes appeared to be blocked. The nevomelanocytes of 4 of the 9 specimens treated with DMBA for greater than or equal to 82 days (9-16 DMBA applications), showed atypical enlarged nuclei with mitotic figures. Since atypia is one criterion for identifying precursors of transformed cells, the model of human nevi grafted onto nude mouse skin may be useful for studying the various steps involved in the progression of benign melanocytic nevi to malignant melanoma.

Characteristics of cultured human melanocytes isolated from different stages of tumor progression

Normal melanocytes and melanocytes of normal nevi, primary melanoma in the radial (RGP) and vertical (VGP) growth phases, and metastatic melanoma exhibited and maintained phenotypic differences when grown in tissue culture or in experimental animals. Only metastatic and VGP primary melanoma cells were tumorigenic in athymic nude mice and had nonrandom chromosomal abnormalities involving chromosomes 1, 6, and 7. The colony-forming efficiency in soft agar was also highest in these two cell types. A cell line of RGP primary melanoma had characteristics of both benign and malignant cells: nevus-like morphology; nontumorigenicity in nude mice; but karyotypic abnormality of chromosome 6. It also had a ganglioside pattern similar to that of normal melanocytes but not melanomas, i.e., a high GM3 ganglioside content compared to the amounts of GM2, GD2, and GD3 gangliosides. Binding of monoclonal antibodies secreted by hybridomas generated by immunization of mice with VGP primary and metastatic melanoma was highest with cells and supernatants of cultures from advanced melanoma and least with nevus cells. There was no binding to normal melanocytes except with the monoclonal antibodies specific for nerve growth factor receptor or 9-O-acetyl-GD3 ganglioside. On the other hand, monoclonal anti-nevus antibodies bound to melanocytes, nevus cells, and RGP primary melanoma cells but not to VGP primary or metastatic melanoma cells. Cultured human melanocytic cells appear to be a unique model for the study of tumor progression.

The role of lymph node dissection for clinical stage I malignant melanoma of intermediate thickness (1.51-3.99 mm)

The survival times of patients who had an elective regional lymph node dissection was compared with that of those who did not undergo the procedure in a database of 72 patients with clinical Stage I melanoma of intermediate thickness (1.51-3.99 mm). All of the patients had been followed for 5 years or longer or until death. No significant differences were found in other reported prognostic factors, suggesting that the two groups were comparable. By multivariate analysis, a low mitotic rate, intermediate patient age, and the presence of an infiltrative lymphocytic response were found to be associated with favorable survival. There did not appear to be any association of elective regional lymph node dissection with survival; and it was concluded that such therapy should not be regarded as "standard" for clinical Stage I melanoma of intermediate thickness.

The dysplastic nevus

Dysplastic nevi are distinctive cutaneous nevomelanocytic lesions that can be recognized clinically and histologically. They were first described as markers of risk for melanoma in members of hereditary melanoma-prone kindreds. Subsequently, they have been discovered in a significant fraction of patients with sporadic melanoma, and in apparently normal members of the community. It is likely that they constitute markers of risk for melanoma in these populations as well, but that the risk is much less than in members of melanoma-prone kindreds. Beyond their role as risk markers, there is evidence that dysplastic nevi may act as precursors of some melanomas. Thus, their recognition offers an opportunity for analysis of pathogenetic mechanisms in cutaneous melanoma. Most dysplastic nevi, however, are completely stable over long periods of observation. Since up to 5% or even more of the population may bear one or more of these common lesions on their skin, it is important that the profession does not create an epidemic of cancer-phobia by over-emphasizing the significance of a dysplastic nevus. Patients with dysplastic nevi should adopt sensible patterns of skin care.

High risk of malignant melanoma in melanoma-prone families with dysplastic nevi

The risk of hereditary cutaneous malignant melanoma was evaluated in 401 members of 14 families with an autosomal dominant form of melanoma. We documented 127 primary melanomas in 69 family members, including 39 new melanomas diagnosed in 22 study participants from the time of first examination through a maximum of 8 years of follow-up. The 39 newly diagnosed melanomas occurred only in family members with dysplastic nevi, a known precursor of familial melanoma. Of 77 patients with dysplastic nevus syndrome without prior melanomas, 4 developed their first melanoma during prospective follow-up, as compared with 0.03 cases expected. The prospective age-adjusted incidence for melanoma was 14.3/1000 patients with dysplastic nevus per year, with a cumulative melanoma risk (+/- SE) of 7.2% (+/- 3.6) at 8 years. The actuarial probability of melanoma developing in family members with dysplastic nevi was 56.0% (+/- 10.1) from age 20 to age 59. This study confirms that dysplastic nevi are clinical markers of high risk for, and precursors of, hereditary melanoma.

Primary melanoma cells of the vertical growth phase: similarities to metastatic cells

Three primary and 16 metastatic melanoma cell lines were established from primary and metastatic lesions of 4 patients with malignant melanoma. Comparison of metastatic melanoma cells with cells of the vertical growth phase (VGP) or late primary melanoma from the same individual revealed, generally, a shorter population-doubling time, growth to a higher cell density, higher tyrosinase activity, and more pigmentation in metastatic cells. Conversely, primary and metastatic melanoma cells had similar morphology, plating efficiency, and tumorigenicity in nude mice. Karyotypic analysis revealed clonality and nonrandom abnormalities in chromosomes 1, 6, and 7 in cells of the primary and metastatic lesions of the 3 patients studied. Few differences were found in the expression of melanoma-associated antigens on short-term and long-term cultured cells by tests with monoclonal antibodies in mixed hemadsorption assays, flow cytometry, and radioimmunoassays. Our results indicate that cells cultured from the VGP but not from the radial growth phase of primary melanoma are similar to metastatic melanoma cells.

A study of tumor progression: the precursor lesions of superficial spreading and nodular melanoma

Six evident lesional steps of tumor progression form the neoplastic system that affects the human epidermal melanocyte: 1) the common acquired melanocytic nevus; 2) a melanocytic nevus with lentiginous melanocytic hyperplasia, i.e., aberrant differentiation; 3) a melanocytic nevus with aberrant differentiation and melanocytic nuclear atypia, i.e., melanocytic dysplasia; 4) the radial growth phase of primary melanoma; 5) the vertical growth phase of primary melanoma; and 6) metastatic melanoma. The common acquired melanocytic nevus is viewed as a focal proliferation of melanocytes, destined in most instances to follow a programmed pathway of differentiation that leads to disappearance of the nevus. If the pathway of differentiation is not followed, characteristic lesions result, and such lesions are regarded as the formal histogenetic precursors of melanoma. Such a developmental flaw is termed aberrant differentiation, and the resultant precursor lesion is designated melanocytic dysplasia. The vast majority of melanocytic nevi showing melanocytic dysplasia are terminal lesions that do not progress to melanoma. If melanoma is to develop via a precursor lesion, however, the nevus with melanocytic dysplasia is that precursor. When melanomas do develop, they develop focally within the precursor. The resultant primary melanoma itself does not follow a pathway of inexorable expansion of a population of melanoma cells in space and time. Rather, primary melanomas, with the exception of nodular melanoma, also evolve in a stepwise fashion. The first step, termed the radial growth phase, is characterized by the net enlargement of the tumor at its periphery, along the radii of an imperfect circle. Tumors in this stage of development show a characteristic pattern of growth within the epidermis and a distinctive form of invasion of the papillary dermis. Such melanomas are not associated with metastasis, and it is hypothesized that such tumors do not have competence for metastasis. For a melanoma to acquire competence for metastasis it must progress to the next step of tumor progression--the vertical growth phase. This lesional step is characterized by the appearance of a new population of cells within the melanoma, not an expansion of the cells forming the pre-existing radial growth phase. The net growth of the cells of the vertical growth phase is perpendicular to the directional growth of the radial growth phase. As a rule, the cells of the vertical growth phase grow in an expansile fashion, expansile as a balloon expands: a growth form characteristic of metastases.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization of nerve growth factor receptor in neural crest tumors using monoclonal antibodies

The nerve growth factor (NGF) receptor was characterized by using a new series of anti-receptor monoclonal antibodies (MAbs). These MAbs (i) showed significantly greater reactivity with a melanoma cell line expressing higher levels of NGF receptor, (ii) inhibited the binding of 125I-labeled NGF to its receptor, and (iii) immunoprecipitated both metabolically labeled and 125I-labeled NGF affinity-labeled receptor. These experiments defined the receptor as a 75-kDa cell-surface protein. The NGF receptor was visualized by immunoperoxidase staining in tissue sections of human nevi, melanomas, neurofibromas, a pheochromocytoma, and peripheral nerves. Uniform staining of the cytoplasm suggests that, in addition to cell-surface NGF receptors, there is a population of intracellular receptors.

Lack of association between intraocular melanoma and cutaneous dysplastic nevi

The occurrence of uveal and cutaneous malignant melanoma and the dysplastic nevus syndrome in the same individual suggests an etiologic relationship among these diseases. Thus, the dysplastic nevus syndrome could be viewed as marking an increased risk of both cutaneous and ocular melanoma. We postulated that if such a relationship exists, patients with both forms of melanoma should have a high prevalence of dysplastic nevi. We examined 44 patients (31 women and 13 men ranging in age from 20 to 80 years) with uveal melanoma for evidence of cutaneous melanoma and dysplastic nevi. We also examined photographs of 46 patients (24 men and 22 women ranging in age from 19 to 67 years) with nonfamilial cutaneous melanoma to determine the prevalence of dysplastic nevi. We found a 4.5% prevalence of dysplastic nevi in patients with uveal melanoma, significantly lower than the 41% prevalence in patients with cutaneous melanoma (two of 44 patients vs 19 of 46 patients). This study indicates that uveal and cutaneous melanoma are not etiologically linked through dysplastic nevi and suggests that patients with uveal melanoma are no more likely to have cutaneous dysplastic nevi than the general population.

Phenotypic characteristics of cells derived from precursors of human melanoma

Of 66 specimens from benign melanocytic nevi, including common acquired and congenital nevi, Spitz tumors (epithelioid cell nevi), and melanocytic nevi with dysplasia, 57 could be grown in tissue culture. The cultured cells were identified as melanocytes by the presence of premelanosomes and melanosomes. Cells from 28 of 32 nevus cultures grew in an anchorage-independent way in soft agar with a colony-forming efficiency between 0.001 and 1%. Clones derived from single cells and soft agar-selected colonies showed marked phenotypic heterogeneity, but all had a limited life span and did not undergo transformation in culture. These cells were nontumorigenic in nude mice. Cultured nevus cells expressed antigens present on melanoma but absent on normal fibroblasts and/or melanocytes as tested with monoclonal anti-melanoma antibodies. The anti-melanoma antibodies bound equally well to dysplastic, congenital, and common acquired nevi. Antigens are released by nevus cells similar to melanoma cells.

Familial cutaneous malignant melanoma: autosomal dominant trait possibly linked to the Rh locus

Segregation and linkage analyses were undertaken in families with multiple cases of cutaneous malignant melanoma (CMM) and a recently-described melanoma precursor, the dysplastic nevus syndrome (DNS). Clinical and laboratory data, including 23 genetic markers, were collected on 401 members of 14 high-risk kindreds. Pedigree analysis was compatible with an autosomal dominant mode of inheritance for the familial CMM trait. Although a similar model probably applies to the DNS trait as well, segregation analysis could not confirm the presence of a major locus. However, linkage analysis suggested that an autosomal dominant model was appropriate for the DNS, and that a DNS/CMM susceptibility gene may be located on the short arm of chromosome 1, within 30 map units of the Rh locus [maximum logarithm of odds (lod) score = 2.00].

The familial occurrence of cutaneous melanoma, intraocular melanoma, and the dysplastic nevus syndrome

The occurrence of cutaneous melanoma and intraocular melanoma as double primary cancers in the same patient and in different members of the same family has suggested that these two forms of melanoma are etiologically related. It is theoretically possible that the link between these two pigment cell malignancies may be the dysplastic nevus syndrome, and patients with the dysplastic nevus syndrome may have an increased risk of intraocular melanoma and cutaneous melanoma. We studied two new kindreds in which cutaneous melanoma, intraocular melanoma, and the dysplastic nevus syndrome occurred and conducted neuro-ophthalmologic examinations of 26 patients with hereditary cutaneous melanoma or the dysplastic nevus syndrome, or both. In the one family studied in detail, the cutaneous melanoma predisposition came from the paternal bloodline, whereas the intraocular melanoma occurred in the maternal bloodline. The ophthalmologic examinations disclosed neither intraocular melanoma nor suspicious or atypical choroidal nevi. Our limited data suggested that the association of intraocular melanoma with cutaneous melanoma and dysplastic nevus syndrome may be coincidental.

Skin markings in malignant melanoma

Photographic analysis of the skin markings in 92 malignant melanomas (66 superficial spreading, seven nodular, 12 acral lentiginous, and seven lentigo maligna melanomas) was undertaken. Skin markings are uniformly eradicated in areas of vertical growth phase disease and sometimes in areas of regression. Not only were skin markings always preserved in areas of radical growth phase disease, but they were sometimes accentuated. For all types of melanoma, loss of skin markings is a poor diagnostic criterion because it is a late sign associated with invasion of the dermis and thus a deteriorating prognosis.

Dysplastic nevi on the scalp of prepubertal children from melanoma-prone families

Four prepubertal children, all members of melanoma-prone families, developed pigmented scalp lesions that were diagnosed as dysplastic nevi. In three cases, the scalp lesions were the only evidence that the children were affected by the dysplastic nevus syndrome, a distinctive clinicopathologic entity that identifies persons at increased risk of malignant melanoma. In general, the skin of family members with dysplastic nevus syndrome does not show characteristic lesions until just prior to or with the onset of puberty. The presence of dysplastic nevi on the scalp may permit identification of at least some high-risk family members well prior to puberty. This should facilitate the early implementation of a melanoma prevention program for susceptible individuals and help ensure that melanomas are diagnosed early in their natural history, at a time when they are surgically curable.

Immunoperoxidase localization of lymphocyte subsets in the host response to melanoma and nevi

Using an avidin:biotin immunoperoxidase system with monoclonal antibodies to lymphocyte subsets, we have investigated the host response to malignant melanoma and melanocytic nevi in frozen sections. Eight primary melanomas, eight metastases, three dysplastic nevi, and two dermal nevi were studied with antibodies T11, T4, T8, and B1. Sections were read in a semiquantitative manner by two observers. Virtually all lymphocytes in these lesions were T-cells (T11 positive). In all primary melanomas, in the majority of metastases, and in all dysplastic nevi, both T4- and T8-positive cells were present. In two of eight metastases, tumor cells stained with T4, and in one case, melanoma cells stained with B1 antibody. The host response to melanoma involves primarily T-cells and includes both the helper:inducer (T4) and suppressor:cytotoxic (T8) subsets.

Optimal resection margin for cutaneous malignant melanoma

Cutaneous malignant melanoma has traditionally been treated by "wide" local excision with a 5-cm margin of normal skin about the tumor. The rationale of wide excision for melanoma has never been clearly defined, but the procedure is known to be effective in preventing local recurrence. We studied 105 patients who had 109 primary melanomas in 1977 and related margin width of the definitive excision to the presence of satellites, to the subsequent development of local recurrence and in-transit metastases, and to survival. Survival was not dependent on margin width, and there were no incidences of local recurrence. Satellitosis and in-transit cutaneous metastasis indicate that a melanoma is capable of local recurrence; these phenomena occurred only in tumors whose thickness (Breslow) was greater than 2.0 mm. These data provide a rationale for wide excision of "thick" melanomas and support more modest local therapy for thin cutaneous melanoma.

Use of monoclonal antibodies in detection of melanoma-associated antigens in intact human tumors

The use of antimelanoma monoclonal antibodies on tissue sections using a two-step indirect immunoperoxidase technique is reported. Antibodies 691-13-17 and 691-I5-Nu4B reacted with dysplastic nevus cells and all melanomas tested, but not with normal skin melanocytes, intradermal nevi, or lentigines. Antibody 691-13-17, directed against DR antigen, reacted also with Langerhan's cells, macrophages, and a subpopulation of lymphocytes. Antibody 691-I5-Nu4B reacted only with melanomas. The technique allows analysis of the expression of antigens by tumor cells in situ.

Expression of DR antigens in freshly frozen human tumors

DR antigens are thought to function as differentiation antigens and to restrict immune recognition between T cells and B cells, monocyte/macrophages, Langerhan's cells, and endothelial cells. These antigens are commonly found on tissue culture lines from metastatic melanomas and tumors of lymphocyte derivation but are notably uncommon on cell lines from other malignancies. Using frozen tissue sections, a monoclonal antibody (WI 691-13-17) known to detect an epitope common to all DR alloantigens on the beta (light) chain of DR antigens, and a two-step indirect immunoperoxidase technique, DR antigens were found on all metastatic lesions tested and on many primary tumors and their histogenetic precursors. The technique of using monoclonal antibodies in indirect immunoperoxidase staining of freshly frozen tissue allows individual cells to be assessed for antigen expression and presumably more accurately reflects in vivo antigen expression than results obtained from cells selected by tissue culture methods.

Dysplastic nevus syndrome: a phenotypic association of sporadic cutaneous melanoma

Clinical photographs of 79 prospectively studied cases of non-familial cutaneous malignant melanoma were reviewed; special attention was directed to the distribution pattern of coexistent melanocytic lesions. A group of 15 patients had moles on the covered buttock area. Seven of these patients had large clinically atypical nevi, and biopsies of these nevi showed severe melanocytic dysplasia. Residual elements of melanocytic dysplasia were identified in five of the primary melanomas in this group of patients. It is suggested that these patients represent a distinctive syndrome, the Dysplastic Nevus Syndrome (DNS) and that they are at increased risk for development of primary cutaneous malignant melanoma. The clinically and histologically distinctive dysplastic nevi of these patients are identical to the precursor lesion for melanoma that we have previously described in a familial context, the B-K mole syndrome. This paper represents the first description of this form of dysplasia in non-familial melanoma.

Specific immunoreactivity of hybridoma-secreted monoclonal anti-melanoma antibodies to cultured cells and freshly derived human cells

The specificities of monoclonal antibodies against melanoma cells were analyzed using radioimmunoassay, mixed-hemadsorption assay, and quantitative absorption on a variety of malignant and nonmalignant cells. Three of the six hybridoma-secreted antibodies bound to the majority of melanoma cell lines, melanoma tumors, and astrocytoma cell lines as well as to all normal and Epstein-Barr virus-transformed lymphocytes tested. The binding pattern coincides with the presence or absence of the DR antigen on human cells. Conversely, two other antibodies, 19-19 and Nu4B, detected two different antigens common to melanoma and astrocytoma cells only. Cloning of melanoma cells resulted in establishment of DR-positive and DR-negative clones, with the binding of Nu4B antibody retained in all.