Anti-Bacterial Reactivity of Human Monoclonal Polyspecific Natural IgM Antibodies — a Basic Defence Mechanism Against Infectious Agents

Abstract

An optimized human hybridoma technique may be a powerful tool for studying the B lymphocyte repertoire (antibody specificities, genetic elements) of healthy individuals and patients. The development of a human-mouse heteromyeloma (Grunow 1988) as a fusion cell line enabled us to immortalize human lymphocytes from different immune organs with a frequency comparable to the mouse system. To establish specific IgG-producing hybridomas against tetanus toxin lymphocytes from boosted donors were fused after an optimized period of time (Jahn 1989a). However, when lymphocytes from the spleen or peripheral blood were used for fusion, the majority of hybridomas were shown to secrete IgM (Jahn 1988; Jahn 1989b). A distinct population of these “natural” IgM antibodies (circulating in the non-immunized individual) was characterized to bind to different autoantigens and to foreign material of bacterial or viral origin (Casali 1987; Jahn 1989b). So-called polyspecific natural antibodies were first described to occur in fusions of fetal and newborn mouse lymphocytes (Dighiero 1983; Ternynck 1986).