Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

A limiting dilution microculture system, supplemented with a source of interleukin-2 (IL-2), was employed to evaluate the frequency of Moloney-murine leukaemia/sarcoma virus (M-MuLV/M-MSV)-specific cytotoxic T-lymphocyte precursors (CTL-p) which also exhibited NK-like activity. Spleen cells, obtained from M-MuLV/M-MSV regressor mice, were restimulated in bulk secondary mixed leucocyte-tumour cell cultures (MLTC), and subsequently plated in a culture medium supplemented with two different supernatants (SN) produced following PMA-stimulation of the same EL-4 thymoma cell line. SN 20, obtained from the cell line maintained in vitro, contained IL-2 and only negligible amounts (less than 3 U/ml) of interferon (IFN), while SN 19, obtained after passage of the ascitic form of EL-4 thymoma in syngeneic mice, contained both IL-2 and IFN in high titres. The frequency of CTL-p specific for MBL-2 lymphoma cells was high and comparable in cultures supplemented with both SN (1/2 X 84 cells and 1/2 X 40 cells, respectively), while the frequency of CTL-p directed against NK-susceptible YAC-1 target cells was low in SN 20 (1/90 cells) and high in SN 19 (1/5 X 40 cells). An analysis of individual microcultures established at low cell dose (1 cell/well) indicated that specific and NK-like activity could be ascribed to the same precursor cells. Furthermore, using different long-term CTL clones, we observed that, after passage in SN 20, double-reactive clones gradually lose the capacity to lyse NK-susceptible targets, while most of MBL-2 specific clones acquired NK-like activity following a few passages in SN 19. Therefore, the induction of NK-like activity is reversible and may be modulated by soluble factors present in supernatant in which CTL clones are maintained. Double-reactive clones were unable to lyse NK-resistant allogeneic tumour cells or normal syngeneic blast cells. A few clones cross-reacting with H-2d alloantigens also exhibited NK-like activity when maintained in SN 19. The different pattern of CTL clone activity was associated with a morphological change in the clones themselves: the acquisition of double activity was accompanied by an increase in cell size and the appearance of numerous cytoplasmic granules. All CTL clones were phenotypically Thy-1+ and Lyt-2+ on indirect immunofluorescence and complement-dependent cytotoxicity investigation.(ABSTRACT TRUNCATED AT 400 WORDS)

Type

Journal article

Journal

Immunology

Publication Date

02/1985

Volume

54

Pages

265 - 274

Keywords

Animals, Antibodies, Monoclonal, Cells, Cultured, Cytotoxicity, Immunologic, Interferons, Interleukin-2, Isoantibodies, Killer Cells, Natural, Leukocyte Count, Mice, Mice, Inbred C57BL, T-Lymphocytes, Cytotoxic, Viruses