Suppressor cell activity in melanoma patients. II. Concanavalin A-induced suppressor cells in relation to tumor growth and suppressor T-cell subsets

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Abstract
The relative proportions of T, B and Tγ suppressor cells were determined sequentially in peripheral blood of melanoma patients before and after surgery. Concanavalin A (Con A)‐induced suppression against lymphocyte mitogenesis of melanoma patients and age‐matched controls was measured concurrently. The mean percentage of Tγ cells was significantly higher (p < 0.001) in melanoma patients before surgery (21.8 ± 5.4) compared to a group of age‐matched controls (14.9 ± 5.4). There was a tendency for the proportion of Tγ cells in patients to decrease after surgery, although the relative levels of Tγ were still significantly elevated (p < 0.05) 6–8 weeks after surgery when compared to normal controls. The mean percentage of T and B cells in melanoma patients before and after surgery was comparable to that observed in normal controls. The degree of Con‐A‐induced suppression in patients increased significantly after surgery particularly at 6–8 weeks (p < 0.02). No difference in Con‐A‐induced suppressor cell activity was observed between melanoma patients and controls before or after surgery. An inverse relationship was found between the amount of Con‐A‐induced suppression and percentage of Tγ cells in melanoma patients before surgery. Similar associations were not apparent in patients after surgery or in normal control populations. The inverse correlation of Con‐A‐induced suppression with Tγ cell numbers suggests that the former may measure potential suppressor cell activity whereas the Tγ cells may indicate active suppressor cells. The significance of these findings for the monitoring of suppressor cell activity in vivo and their role in suppression of immune responses in melanoma patients is discussed.