Human PBMCs from healthy donors were cultured with 100 U/ml rIL-2 for up to 5 weeks and tested at short and long activation times for the ability to mediate CD3 and CD16 targeted cytotoxicity using chemically cross-linked bispecific antibodies. At each period, LAK activity was augmented with the use of bispecific antibodies (BA), whereas interestingly enough, at later periods (4-5 weeks) when CD16 positive lymphocytes are not present by flow cytometry, CD16 targeted cytotoxicity was induced. We suspected the possibility of CD16 expression on activated T cells and have purified the T cell subpopulations to see the targeted cytotoxicity. Populations enriched for T cells by Percoll density centrifugation, treatment with anti-CD16 plus complement or sorting for CD5+ cells, were all able to mediate CD16 targeted cytotoxicity following activation with rIL-2. These data suggest that IL-2 activated T cells express CD16 in addition to CD3.