Patients immunized with rhGM-CSF as an adjuvant may develop peripheral blood T-cell responses to rhGM-CSF. A total of 2 × 10⁵ PBMC were incubated with increasing concentrations of rhGM-CSF or ovalbumin as a negative control irrelevant antigen. At the end of a 5-day incubation, cultures were pulsed for 8 hours with 1 μCi ³H-thymidine and the incorporated radioactivity counted. The results are reported as the mean cpm and standard deviation of triplicate wells.