Demonstration of the increase in serine esterase-positive T cells in hairy-cell leukemia patients undergoing alpha-interferon therapy.

An increased number of serine esterase non-B lymphocytes including CD4+ helper/cytotoxic cells were observed in hairy-cell leukemia patients during (56 +/- 18) and immediately post (52 +/- 16) alpha-interferon therapy compared with pretreatment status (17 +/- 5) and normal donors (29 +/- 3). This increase in lymphocytes bearing one of the putative cytotoxicity-linked proteins was paralleled by a higher cytotoxicity towards K562 cells in the NK and LDCC assays during therapy and similarly, but to a much reduced level, against the hairy-cell derived JOK-1 target cells. Phenotypically, a higher percentage of non-B cells also expressing DR or CD11 antigens were seen in the HCL patients during IFN therapy. In lymphocyte target binding assays, a high affinity of effector to target conjugate formation was observed when either of the hairy cell lines JOK-1 or Hair-M was chosen as targets for IFN-therapy effector cells. Although predominantly CD4+ cells exhibited the in vitro affinity for effector/target conjugation with autologous HCs, the polarisation of serine esterase activity towards the E/T membrane contact area was shown by both CD4+ and CD8+ cells during a short incubation period and before target cell death.