Indirect leukocyte migration assay in patients with malignant melanoma.

Leukocytes from 72 melanoma patients and 75 control donors were examined in a two-stage (indirect) leukocyte migration assay, using formalin-fixed melanoma cells (FMC) and control, normal or non-melanoma tumour cells (FCC) as the source of antigen. Inhibitory supernatants were produced significantly more often by cultures of melanoma leukocytes and FMC than by melanoma leukocytes and FCC or control leukocytes and FMC or FCC. Reactive leukocytes were most frequently derived from stage II patients (65%), followed by stage I patients with tumour present (58%), stage III patients (29%) and stage I patients without detectable tumour (20%). The likelihood that a melanoma patient's leukocytes would react increased progressively with the number of different FMC preparations tested. A similar, though less steep increase in reactivity was seen with control donor leukocytes and different FMC preparations. No significant increase in reaction frequency was seen with melanoma or control leukocytes exposed to increasing numbers of different FCC preparations. Significant discrimination between melanoma patients' and control donors' leukocytes was achieved with FMC from both primary and metastatic tumours. Concordance of positivity or negativity was seen in 60% of concurrent one-stage and two-stage leukocyte migration assays.