HPC growth inhibition by T-cell clone 6.2. T-cell clone 6.2 is preincubated with BM cells at indicated T-cell:BM cell ratios for 4 hours at 37°C. The cells were then transferred into semisolid HPC growth medium and cultured in cell culture dishes to allow HPC growth. The colony formation in semisolid medium is determined by light-microscopy after 10 days. Percent inhibition of the HPC growth was determined as follows: % Inhibition = (1 − No. of Colonies in the Presence of T-Cell Clone/No. of Colonies in the Absence of T-Cell Clone ) × 100%.