Antigens on melanoma cells detected by leukocyte dependent antibody assays of human melanoma antisera

Paraneoplastic syndromes, tumor markers, and other unusual features of malignant melanoma

Malignant melanoma is a neoplasm associated with a wide variety of paraneoplastic syndromes. In this review the many paraneoplastic syndromes associated with malignant melanoma are critically reviewed. Unusual nonparaneoplastic associations with malignant melanoma and tumor markers for malignant melanoma are discussed.

Phase II study of vaccinia melanoma cell lysates (VMCL) as adjuvant to surgical treatment of stage II melanoma. II. Effects on cell mediated cytotoxicity and leucocyte dependent antibody activity: immunological effects of VMCL in melanoma patients

Patients with stage II melanoma were vaccinated with vaccinia virus-induced melanoma cell lysates (VMCL). The vaccine contained viable vaccinia virus, membranous fragments and no intact nuclei. A number of antigens defined by monoclonal antibodies were detected in the vaccine including the ganglioside GD3 and DR antigens. Administration of the vaccine was associated with depression of natural killer cell activity against melanoma and K562 target cells in the first 3-6 months of treatment. Leucocyte dependent antibody (LDA) activity against melanoma cells was induced or increased in titre in approximately half of the patients studied. Continued vaccination was associated in a number of patients with a decrease in LDA titres. Studies on a small sample of patients revealed that this was associated with the development of serum factors which inhibited LDA activity. LDA activity appeared directed to non-MHC antigens on melanoma cells which were of at least two specificities. One specificity which was shared with antigens on a number of non-melanoma carcinoma cells was removed by absorption on fetal brain and may be similar to oncofetal antigens described by other workers. Reactivity against melanocytes was induced in some patients and may underline the development of vitiligo in several patients. These results suggest that vaccines prepared from VMCL may be a favourable method for increasing immune responses against melanoma.

Review of melanoma antigens recognized by monoclonal antibodies (MAbs). Their functional significance and applications in diagnosis and treatment of melanoma

The introduction of monoclonal antibody techniques has led to a rapid advance in information concerning antigenic structures in melanoma cell membranes. These have been classified according to the extent of their expression on cells of other tissues, but it is evident that a more precise classification based on their biochemical nature is possible. Several monoclonal antibodies appear to define antigens restricted to melanoma cells and fetal tissues. Many antibodies recognize antigens shared with gliomas and nevi, whereas other groups can be defined which recognize antigens on melanocytes or other carcinomas. One of the commonly detected antigens was shown to be a high molecular weight (MW) proteoglycan which may be involved in reactions with other cells and the intercellular matrix. A second antigen was shown to be a ganglioside which may have receptor functions in cells. A third was shown to be a glycoprotein with iron transport functions. The latter antigen and the large MW proteoglycan have been a focus of attention for in vivo targeting studies in treatment and diagnosis. The ganglioside, large MW proteoglycan and a melanocarcinoma antigen may be detected in the circulation of patients and are being evaluated for monitoring of disease activity in patients with melanoma. Several monoclonals may be of value in histological evaluation of melanoma, e.g. diagnosis of preneoplastic lesions, metastatic lesions of unknown origin and identification of cell structures related to metastatic behaviour in the host. Further studies should help to define cellular structures recognized by the immune system in humans.

Immunity to melanoma associated antigens detected by both leukocyte adherence inhibition and antibody dependent cellular cytotoxicity assays

Two different assays, leukocyte adherence inhibition (LAI) and antibody dependent cellular cytotoxicity (ADCC) have been used to measure the immune responses of 69 melanoma patients, 116 patients with other tumours and 64 normal controls to a number of melanoma and control antigens. Using the LAI test, melanoma patients were significantly more reactive (43-69% positive) than normal controls (7-32% positive) to membrane extracts from 3 to 6 melanoma cell lines, and 4 to 6 extracts of melanoma biopsy specimens. However, the proportion of patients with other tumours reacting with 3 of these extracts was similar to melanoma patients. Melanoma patients were more reactive to the melanoma extract than to extracts of normal skin, normal muscle and 2 breast cancer cell lines. ADCC tests were used to detect anti-melanoma antibodies in patient sera. Preferential reactivity by melanoma patients was detected towards only 2 of the 6 melanoma cell lines tested--53% of 55 melanoma sera reactive to LiBr compared with 28% of 79 sera from patients with other tumours and 17% of 29 normal sera (P less than 0.05); 42% of 31 melanoma sera reactive to MM127 compared with 18% of 22 sera from other tumour patients (n.s.) and 5% of 20 normal sera (P less than 0.005). Melanoma patients tested against a number of melanoma cell lines by ADCC or antigen extracts by LAI generally reacted with one or more, but not all of them. Thus, incomplete cross-reactivity between different melanomas was observed. There was no correlation between results of the same patient in the 2 tests.

Absence of melanoma specificity in the reactivity of melanoma patients' sera with cultured allogeneic melanoma cell lines

While patients with melanoma are known to produce antibodies against melanoma cells, the tumor specificity of these reactions has not been well documented. Using the sensitive mixed hemadsorption assay we have identified antibody against one or more of nine different cultured melanoma cell lines in only nine of 48 patients with melanoma. Reactivity against melanoma cell lines was seen only in females, 9/27 versus 0/21 males. The strongest melanoma reactivity was seen in sera which also contained lymphocytotoxic antibody. The reactivity was not melanoma specific because it could be removed by absorption either with pooled platelets, nonmelanoma tumor cells or in two cases, by both. We conclude that the occurrence of specific antimelanoma antibodies against common or shared surface melanoma associated antigens is an uncommon event in melanoma patients not receiving specific active immunotherapy. The clinical significance of the observed reactivity and whether it is directed against cancer associated determinants, fetal antigens, or normal tissue or histocompatibility antigens requires further study.

Malignant melanoma of the skin occurring during pregnancy

The clinical course of melanoma of the skin diagnosed during pregnancy was compared with a control population of women with melanoma that occurred during the childbearing years, as recorded by the Connecticut Tumor Registry. The survival at three and five years for the 12 patients whose melanoma developed during pregnancy was significantly worse than for 175 nonpregnant controls (five-year survival 55% for pregnant women compared with 83% for nonpregnant women, P less than 0.05). Melanoma during pregnancy tended to occur more often on the trunk, a prognostically poor site, and at more advanced stage of disease than in nonpregnant women. However, when pregnant patients were matched to random, nonpregnant case-controls by age, anatomic site of primary lesion, and stage at diagnosis, three- and five-year survivals were not different. The number of pregnant women observed among this group of women was not substantially higher than expected, when estimated from Connecticut live birth rates: 13.3 pregnancies were expected and 12 pregnant women were actually observed. However, an unknown number of pregnancies end in abortion, making more exact estimates impossible. Melanoma occurring during pregnancy usually carries a poor prognosis, but once the disease is diagnosed, the course is not worse than expected considering stage of disease and primary site.

Trophoblast transferrin and transferrin receptors in the host--parasite relationship of human pregnancy

Transferrin and specific transferrin receptors are demonstrated on the microvillous surface of syncytiotrophoblast in human immature and term placentae by immuno histological techniques with the use of light and electron microscopy. That the distribution of transferrin is limited to the materno-foetal interface supports the hypothesis that binding of maternal transferrin to trophoblast receptors is involved in the process of iron transport to the foetus. Parallel studies with baboon placentae demonstrate the presence of trophoblast receptors which bind both baboon and human transferrin, thereby putting forward an experimental model which might be used to test the biological significance of placental transferrin receptors in primates. In addition, investigation of a large number of human cell lines shows that many transformed cells, but no normal cells (such as blood lymphocytes) or cells from primary culture (such as neonatal foreskin fibroblasts), possess the ability to bind transferrin to their membranes. These findings suggest that transferrin receptors may play important biological roles in addition to that of iron transport from mother to foetus. One such role could be the limitation of iron in intervillous spaces, thus depriving iron-requiring microorganisms of iron, hence serving as a non-specific factor of resistance for placentae. Another role for foetal transferrin receptors on trophoblasts could be to bind maternal transferrin at the materno-foetal interface, thus frustrating maternal immunosurveillance. This is similar to a mechahism used by schistosomes in the host-parasite relation where host proteins are bound by the parasite to escape immunological recognition. The presence of transferrin receptors on transformed cells suggests that this mechanism might also be employed by tumour cells. Finally, in view of previous studies which show that transferrin is required by stimulated lymphocytes to pass from the G1 to the S phase of cellular replication, it is proposed that trophoblast transferrin receptors could limit the amount of transferrin in intervillous spaces and thus impede the proliferation and possible cytotoxicity of maternal activated lymphocytes at the materno-foetal interface.

The relationship of marital status to survival from melanoma

As an indirect test of the hypothesis that prior pregnancy has a favorable influence on prognosis in melanoma, the relation of marital status to survival among melanoma patients was examined in data gathered by the Connecticut Tumor Registry, 1935--1973. Compared to women who had never been married, ever-married women with the disease had a slightly increased survival rate, but the difference was not statistically significant. If a difference between parous and nulliparous women in survival from melanoma truly exists, it is probably a small one, and could be due to differences in characteristics other than childbearing.

[Limits and possibilities of neoplasm immunotherapy]

Immunological treatment of malignant human tumors has so far met with little success. Based on methods and insights obtained by investigation of corresponding animal models, this article attempts to elucidate the reasons for this failure and to suggest ways and means to improve immunotherapeutic approaches to human neoplasms.

Relationship of cell-mediated cytotoxicity against melanoma cells to prognosis in melanoma patients

The cell-mediated cytotoxicity (CMC) of blood mononuclear cells against cultured human melanoma cells was measured in patients after surgical removal of localized melanoma, at a time when they were considered on clinical grounds to be free of melanoma. It was found that the distribution of CMC values against melanoma cells in melanoma patients was different from that in control subjects, and several sub-populations of melanoma patients were evident on the basis of these measurements. No difference in distribution of CMC values was found against non-melanoma cells, which suggested the changes were specific for melanoma. The proportion of patients with recurrence of melanoma was compared between the patient groups with low, normal or high CMC values against cultured melanoma cells after surgery. Analysis for periods extending to 2 years showed that patients with low CMC values after surgery had a significantly higher incidence of recurrence from melanoma than patients with normal or high CMC values. These results suggest there may be a sub-group of melanoma patients who have intrinsically low CMC against melanoma cells, and that this may be an important predisposing factor in the development of recurrent melanoma.

Blocking factors against melanoma leucocyte-dependent antibody: relationship to disease activity in melanoma patients

Previous studies have shown that many melanoma patients have cytotoxic leucocyte-dependent antibody (LDA) which is inhibited by factors in their sera. These factors were shown to be small molecular weight glycoproteins which could also be identified in the supernatants of melanoma cultures, and which were therefore most likely to be melanoma cell surface antigens. The present studies have shown that these blocking factors against melanoma LDA can be detected in patients with primary melanoma, and that the levels of this activity show an inverse correlation with the levels of LDA in the sera of melanoma patients. The appearance of melanoma LDA after surgery for localized melanoma was shown in approximately a third of the patients, and this pattern was shown to result from the disappearance of the LDA blocking activity after surgical removal of the melanoma. Assays were designed specifically to measure the melanoma LDA blocking factors by plasmapheresis. It is not yet known whether the melanoma LDA blocking activity has correlation with tumour growth in melanoma patients. The potential value of measuring this activity to assess response to therapy was shown by studies designed to remove the blocking factors by plasmapheresis. It is not yet known whether the melanoma LDA blocking activity has biological significance in regard to tumour growth, but these studies appear to indicate that measurement of these factors in the sera of melanoma patients may provide a useful in vitro monitor of tumour growth in melanoma patients.