Interleukin-1-like activity produced by hybrids constructed with Epstein-Barr-virus-transformed human B lymphocytes and mouse myeloma cells.

Peripheral blood B lymphocytes from a donor with positive tuberculin skin test reaction were transformed into lymphoblastoid cell lines by Epstein-Barr virus and then fused by polyethylene glycol with mouse myeloma cells. Human-mouse hybrid cells producing human IgM monoclonal antibody to purified protein derivative of tuberculin were isolated, and the concentrated supernatant of one of these cell hybrids was tested for the capacity of interfering with DNA synthesis of human and mouse lymphocytes. The hybrid cell supernatant was found to contain soluble factors that increased DNA synthesis in unstimulated human and mouse lymphocytes and that, conversely, decreased DNA synthesis in concanavalin-A-stimulated cells. Gel filtration experiments showed that these antagonistic activities were due to at least two different factors, one of which resembled human interleukin-1 in biochemical and biological properties.