Increase in E. active rosette forming lymphocytes in melanoma patients treated with BCG

Identification of "active" T lymphocytes among effector cells in guinea pigs

Guinea pig T lymphocytes have receptors of different affinity for rabbit red blood cells (RRBC): those binding RRBC immediately are termed "active" T cells; the remainder, which bind RRBC only after longer incubation times, are "non-active" or "late-rosetting" T cells. We have found that these two subpopulations have different functional characteristics. Active T cells could not be stimulated effectively with phytohemagglutinin (PHA), and stimulation with concanavalin A (ConA) increased their DNA synthesis only at high concentrations. The non-active subpopulation responded better to PHA but poorly to ConA. Unseparated (total) T cells, however, responded well to both mitogens, suggesting a helper effect by the active T cells. The presence of monocytes in T-cell cultures further enhanced mitogen-induced DNA synthesis. Active T cells were not present in guinea pig bone marrow, whereas they constituted 10% of all lymphocytes in the thymus, 13% in the spleen, 29% in lymph nodes, and 32% in the peripheral blood. After administration of antigen in vivo, the number of active T cells in the regional lymph node increased, whereas the number of total T cells did not change. The similarity of the active T cell populations in guinea pigs and humans increases the usefulness of these animals for preclinical tests of potential new immunomodulating agents.

Immunological status may predict clinical outcome in BCG treated melanoma

Twenty-seven patients with surgically resected stage II or III malignant melanoma were treated with bacillus Calmette-Guérin (BCG) and followed prospectively to determine whether relapse could be predicted. Peripheral blood mononuclear (lymphocyte plus monocyte) counts (PBM), T and B cell counts, phytohaemagglutinin (PHA) cytotoxicity, PHA transformation, antibody-dependent cell-mediated cytotoxicity (ADCC) and serum immunoglobulin concentrations were studied before and during therapy. Patients ultimately classified as having a poor clinical outcome (inoperable recurrence) were compared with those with a more favourable outcome. Prior to therapy, poor outcome patients had lower PBM and T cell counts but there was some overlap. After three months, these differences were more pronounced. Low PHA cytotoxicity was also associated with poor outcome; again the differences were more apparent at 3 months than prior to therapy. These results suggest that PBM, T cell counts and PHA cytotoxicity may predict poor outcome some months before inoperable recurrence in apparent clinically.

Immunotherapy of melanoma

Malignant melanoma is a disease characterized by clinical evidence of host defense, possibly immunologically mediated. It is a disease which tends to be refractory to both radiotherapy and chemotherapy. Immunotherapy has been used in three phases of the disease. 1. Intralesional immunotherapy with a nonspecific immune adjuvant in patients with local intradermal or soft tissue recurrence. This treatment produces approximately 15% regression of both injected and uninjected lesions, and about 60% regression of injected lesions only. Both clinical and laboratory evidence suggests that this regression is immunologically mediated. 2. Patients with surgical removal of all clinically demonstrable tumor, either primary disease alone or regional node recurrence, active nonspecific, and specific, immunotherapy has been used in an adjuvant setting. There is considerable controversy about the benefits accruing to such immunotherapy, but most large scale prospective and randomized studies have suggested that if benefit does result it is modest in degree and probably cannot be measured in terms of increase in cure rate. 3. Immunotherapy has also been used as a nonspecific active adjuvant to single drug or polychemotherapy in patients with disseminated melanoma. Whereas complete response rate may be slightly increased by this maneuver there is no convincing evidence that immunotherapy markedly increases the total objective response rate to polychemotherapy, and survival is only marginally superior when immunotherapy is added to chemotherapy in this setting. Further studies need to be done with active specific immunotherapy with tumor cell membrane extracts; as an adjuvant in patients with minimal body burden of tumor cells; and to study the inaction between chemotherapy and immunotherapy in this disease. Furthermore, studies of chemically defined fractions of either bacterial cell wall or tumor cell extracts must be evaluated both in terms of their ability to augment cell mediated immune responses in the melanoma patient, and also in terms of their ability to induce objective benefit for the patient. The possible use of immunotherapy in patients with primary melanoma has been briefly explored but needs further study. Possible additive effects with radiotherapy and immunotherapy should also be looked at in this disease utilizing high dose fractions and other new forms of radiotherapeutic technique.