Presence of perforin and granzyme B in lysates of PMNs. (A) By immunoadsorption, perforin was found in lysates of freshly isolated T lymphocytes (2 and 1 × 10⁶; lanes 1 and 2, respectively) and freshly isolated PMNs (5 × 10⁶; lane 3), and to a lesser degree in PMNs cultivated for 48 hours in IFN-γ (100 U/mL lane 4; detected by silver staining). The presence of granzyme B in PMN lysates was shown by Western blotting (lane 6). Lane 5 shows the respective negative control (mouse IgG in place of antibody to granzyme B). M represents the molecular size marker. (B) Detection of perforin- and granzyme B-specific message by RT-PCR. RNA was extracted from highly purified PMNs (10⁶) or T cells (10⁶); then, RT-PCR was performed with primers specific for either perforin or granzyme B. The RT-PCR products obtained from PMN RNA were of similar size as those derived from T cells.