Lymphocyte activation by granulocyte macrophage-colony stimulating factor in human bladder cancer

The goal of this study was to investigate the ablative or reductive activity of granulocyte macrophage-colony stimulating factor (GM-CSF) instillations on transitional cell carcinoma marker lesions as well as its ability to increase and/or activate lymphocyte population.

Eleven patients (pts) with newly diagnosed cancer pTa-pT1 were studied. A well-defined marker lesion (< or = 0.5 cm) was left after transurethral resection (TUR). All pts received eight weekly instillations of 300 micrograms of GM-CSF after which cystoscopy with biopsies +/- TUR was repeated. Specimens from adjacent to the lesion mucosa were obtained before and after GM-CSF therapy and processed for ultrastructural study.

The response was complete in six pts (55%), no change in two pts (18%), for a total of 73% response, and all pts were free of disease after one year. Progression was observed in three pts (27%) with no case of muscular invasion. Before treatment, the scarcely detected lymphocytes had morphological characteristics of resting cells. After treatment, the most impressive finding was the detection of lymphocytes with "hand mirror" morphology, suggesting an immunological activation. This finding has not been previously described in the bladder mucosa.

The present study led us to speculate on the use of GM-CSF as a new alternative approach in the management of TCC through immunomodulation.