Christine Burns

Enhancement of cytotoxic and proliferative responses of lymphocytes from melanoma patients by incubation with monoclonal antibodies against ganglioside GD3

SummaryPrevious studies have shown that monoclonal antibodies (M.Ab) to the ganglioside GD3 may induce partial remissions in tumour growth in patients with melanoma. In vitro studies demonstrated that M.Abs to GD3 may also enhance lymphocyte responses to phytohemagglutinin and interleukin 2 (IL2). The present study extended these findings by showing that the IL2-dependent proliferative and cytotoxic response of T cell clones derived from a melanoma patient and a patient with the Vogt-Koyanagi-Harada syndrome were enhanced by pre-incubation of T cells with M.Ab to GD3. The degree of enhancement increased with the duration of pre-incubation from 2 to 24 h and applied to both T4+ and T8+ clones. The potentiation of these responses was not specific for M.Abs to GD3 but was also seen with M.Abs to GD2 and the T10 structure on T cells but not with M.Abs to the transferrin receptor or an isotype control M.Ab. Incubation of lymphocytes from a melanoma patient with M.Ab to GD3 during culture with autologous melanoma cells enhanced the proliferative response to the tumour. The expression of IL2 receptors (Tac epitope) on the T cells showed variable enhancement after incubation with M.Ab to GD3 but the significance of these findings in relation to the mechanism of the enhanced responses is not known. These results suggest that certain M.Abs may stimulate cell-mediated immune responses against tumour cells and that this may provide an additional mode of action of M.Abs against tumours in vivo

Clonal analysis of cytotoxic T lymphocytes (CTL) against autologous melanoma

SummaryThis study investigates the nature and specificity of cytotoxic T lymphocytes (CTL) in patients with melanoma which are able to kill autologous melanoma cells. Interleukin 2 (IL2)-dependent T cell clones from two melanoma patients and a normal subject were generated in mixed lymphocyte cultures (MLC) or mixed lymphocyte tumor cell cultures (MLTC) and propagated for prolonged periods in tissue culture. Analysis of their phenotype by a wide range of monoclonal antibodies (M.Abs) revealed two main phenotypes which depended on whether they expressed Fc receptors detected by Leu 11 M.Abs or not. Leu 11− T cells (referred to as Type 1) were inhibited by M.Abs to T3, T8, and a common HLA, ABC antigen. Conversely Leu 11+ T cells (referred to as Type 2) were inhibited by M.Ab to Leu 11 but not by M.Ab to T3, T8 and the HLA, ABC antigen. Subtypes among Type 1 cells were recognized which depended on their specificity. The most restricted were CTL [Type 1(a)] clones generated only in MLTC which recognized the autologous melanoma cell plus 1 of 11 other melanoma target cells. Type 1(b) CTL clones recognized a larger proportion (approximately 50%) of the melanoma cells. A third category [Type 1(c)] recognized antigens on melanoma cells shared with that on the EBV-transformed B cells used as stimulators in the MLC. Type 2 CTL clones had broad specificity to melanoma and nonmelanoma cells, characteristic of that described for lymphokine activated killer (LAK) cells. The latter were MHC unrestricted but further studies are required to clarify whether the Type 1 CTL clones are MHC restricted or not. The CTL activity of all clones was inhibited by M.Ab to the sheep red blood cell receptor and to the T10 antigens. It is suggested that recognition of these different types of CTL clones may assist future studies on the immune response against melanoma and the nature of antigens recognized by CTL.

Effect of heat inactivation of HIV on specific serum proteins and tumour markers.

The effect on the concentrations of specific serum proteins and tumour markers, of heat-treating samples at 56°C for 30 min to inactivate HIV, was investigated. Statistically significant decreases, that may affect clinical decisions, were observed for α-1-antitrypsin, β-2-microglobulin, IgE, fibrinogen, C***1-esterase inhibitor and CA125. Statistical, but not clinically significant, changes were observed for α-1-acid glycoprotein, C3, haptoglobin, IgA, IgG, IgM and transferrin. A significant decrease in the α-1 band was observed on protein electrophoresis.