Interferon-induced surface alterations in hairy cells. A review.

Hairy cells (HCs), derived from the peripheral blood and spleen of hairy cell leukemia (HCL) patients, constantly displayed both ruffles and microvilli. HCs which were kept in culture for up to three days exhibited extremely polarized and active surfaces with elongated microvilli and exaggerated "spiked" ruffles. Cells derived from 11 cases of HCL were treated with alpha-interferon (IFN) in-vitro and examined by immuno-scanning electron microscopy (immuno-SEM). In 8 cases, up to one-third of the IFN-treated hairy cells displayed deformed surfaces with "bubbling" membrane and markedly villous bud-like formations. Monoclonal antibodies (MoAb), used in conjunction with immuno-gold labeling, facilitated better correlation between these morphological changes and the immunological profiles of the cells before and after interferon treatment in-vitro. Immuno-SEM analyses revealed no remarkable changes in the labeling of HCs with Leu-14 and Leu-M5 MoAbs before and after IFN treatment, even in cases showing membrane changes. However, a significant increase in the labeling intensity for HLA-DR and HLA-DQ was noticed in HCs from cases where IFN-induced membrane changes were evident. A review of the literature on membrane changes in IFN-treated cells proposes that such immuno-ultrastructural alterations might reflect unique interferon-induced membrane reorganization in the target malignant cells.