No abstract

A method of producing human monoclonal antibody by combining somatic cell hybridization technology with the capability of Epstein-Barr virus (EBV) to transform human B lymphocytes is described. Peripheral blood lymphocytes from a donor with positive tuberculin skin test reaction were transformed by EBV and then tested for antibody production to mycobacterial purified protein derivative (PPD) by an enzyme-linked immunosorbent assay. Two EBV-transformed lymphoblastoid cell lines making IgM antibodies to PPD were obtained. One of these cell lines was fused by polyethylene glycol with a murine hypoxanthine-guanine phosphoribosyl transferase-deficient myeloma cell line that had been selected for resistance to ouabain. The human-mouse hybrids were selected in ouabain-containing HAT medium and 11 heterohybridomas producing IgM antibody to PPD were obtained. One of these was cloned by limiting dilution with efficiency at least 20-fold higher than parent EBV-transformed cell line. Heterohybridoma subclones reached levels of IgM antibody as high as 75.0 micrograms/ml of culture medium, whereas IgM production of EBV-transformed B cell clones ranged between 3.0 and 4.0 micrograms/ml.

Autoantibodies reacting with bromelain-treated autologous mouse red blood cells (Br-MRBC) are spontaneously produced by normal mice. In order to understand the biological significance of these autoantibodies, anti-Br-MRBC monoclonal autoantibodies have been prepared and studied for reactivity with a panel of frozen tissue sections from organs of normal mice by direct immunofluorescence. It has been found that the anti-Br-MRBC monoclonal autoantibodies are polyspecific, since they react with cells in multiple organs.

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.