Duck lymphoblasts generated by phytohaemagglutinin (PHA) did not respond to recombinant or Jurkat cell line human interleukin (IL)-2 or possess surface antigens resembling mammalian IL-2 receptors or IL-1 beta. Supernatant fluids from normal and PHA-stimulated duck lymphocyte cultures, and normal and lipopolysaccharide (LPS)-stimulated monocytes, gave negative results in a range of assays for biological activity and immunochemical presence of factors resembling mammalian IL-1 and IL-2. However, supernatant fluids from LPS-stimulated duck monocytes contained IL-6-like activity (up to 35 units/mL) assessed on the 7TD-1 murine cell line. We were unable to demonstrate mRNA that would hybridize to cDNA probes for human IL-1 beta, IL-6, and tumour necrosis factor (TNF) in extracts of blood and lymphoid organs from normal and antigen-stimulated ducks. Because homologous serum or plasma is essential for duck lymphocytes and macrophages to respond to mitogens in vitro, we asked whether this growth-factor-like activity might be caused by substances resembling mammalian cytokines. Serum and plasma were examined for activity consistent with IL-1 and IL-6 on mammalian target cells. None was detected. Instead, both serum and plasma contained inhibitors of human IL-1 beta and IL-6, detected at dilutions up to 1:100. Inhibition by serum was heat (56 degrees C, 30 min) labile but inhibition by plasma was heat stable. The identities and biological functions of these inhibitors remain to be defined.

Animals↗

PubMedDate not supplied

Human monoclonal IgM antibodies from foetal B-cell hybridomas directed against a surface antigen on human tumour cells.

In order to assess the existence of B lymphocytes capable of producing anti-tumour antibodies in non-tumour-bearing individuals, human lymphocytes derived from foetuses and adults were fused with the heteromyeloma cell line CB-F7. By indirect immunofluorescence, 29 out of 4,472 IgM-producing hybridomas (from 8 foetuses and 8 adults) were shown to produce antibodies which bind to colon carcinoma lines Colo205 and SW620, Raji lymphoma cells and small cell carcinoma of the lung. In vitro growth of tumour cells recognized by these antibodies was inhibited. The antibodies also mediated complement-dependent cytotoxicity. All antibodies tested recognized a cell surface molecule of 55 kDa. Southern blot hybridization analysis of hybridoma DNA with a human JH probe showed that the hybridomas were derived from clonally unrelated B cells. These results demonstrate that human foetal and adult B cells from non-tumour-bearing individuals are able to produce IgM antibodies recognizing defined cell surface molecules expressed on some tumour cells.

Adult↗