RT-PCR for TIMP-1. PCR amplification of TIMP-1 cDNA was performed for 20 cycles (except isolated peripheral blood B cells, 30 cycles shown). Lane 1, PA682 (positive control); lane 2, water (negative control); lanes 3 to 5, isolated tonsillar B cells at 0 hours (lane 3), 4 hours (lane 4), and 24 hours (lane 5) stimulation with Staphylococcus aureus Cowan strain I and phorbal 12-myristate 13-acetate; lane 6, isolated peripheral blood B cells.