Figure 1.

Inhibition of ACE-like activity in culture medium abrogates sensitization of target cells with the longer peptide P18IIIB. (a) BALB/c.3T3 fibroblast cells were incubated with 3 µm of peptide P18IIIB (circles) or I-10 (squares) in CTM (open symbols) or in serum-free CTM (closed symbols) overnight in the presence of ⁵¹Cr. Then they were washed three times and used as target cells. (b) Chromium 51-labelled BALB/c.3T3 cells were incubated with 3 µm of peptide P18IIIB (circles) or I-10 (squares) for two hours at 37° (open symbols) or 4° (closed symbols), respectively. Then they were washed and used as target cells. (c) BALB/c.3T3 cells were incubated with 3 µm of peptide P18IIIB (circles) or I-10 (squares) in the presence (closed symbols) or absence (open symbols) of 400 µm of ACE inhibitor, captopril. Then they were washed three times to remove all free peptide and used as target cells. LINE-IIIB cells were used as effector cells. The SEM of triplicate cultures was always < 5% of the mean.