B-cell hybridoma as intraperitoneal tumor model: correlation between tumor growth and monoclonal antibody production.
Murine B-cell hybridoma cells producing an immunoglobulin G1 (K13), specific for human immunoglobulin kappa chains were inoculated intraperitoneally in mice. After intraperitoneal injection of 10(6) K13 hybridoma cells, superficial intraperitoneal implants and ascites developed, resulting in death after 10 +/- 3 days (mean +/- SD). An immunoradiometric assay was developed to measure K13 in murine blood, ascites and culture supernatant. The assay utilized polymer beads coated with human immunoglobulin G. The amount K13 bound to the particles was measured with a 125I-labelled monoclonal rat antibody (LO-MG1-13) specific for mouse IgG1. The assay could be used over a wide working range (2-500 micrograms/l). Kinetic studies suggested that about 10(5) secreting cells were required for detection of K13 in blood. After injection of 10(6) cells, K13 was measurable in blood 1 day later in all animals. Nine of 33 mice injected with 10(5) or less cells survived, and initially showed rising K13 blood levels followed by decreasing blood levels. In conclusion, a close relationship was established between i.p. growth of the hybridoma K13 cell line and the MAb blood levels. The basic concepts of this assay can readily be adopted for other clones with the limitation that pure antigen is needed for solid phase extraction of the MAb from mouse blood.