Hybrids from normal, germ free, nude and neonatal mice produce monoclonal autoantibodies to eight different intracellular structures.

The supernatants of hybrids produced by fusion of splenocytes from normal, germ free, nude and neonatal BALB/c mice with mouse NS-1 myeloma cells were examined for immunofluorescence reactivity with viable and acetone fixed monolayers of syngeneic mouse fibroblasts and mouse 3T3 cells and with viable cell suspensions of syngeneic mouse erythrocytes and thymocytes. The supernatants of 70 out of 419 (16.7%) hybrids from normal mice, 87 out of 627 (13.9%) from germ free mice, 28 out of 240 (11.7%) from nude mice and 42 out of 1020 (4%) from neonatal mice reacted with 8 different intracellular structures in mouse fibroblasts and 3T3 cells, and with rat and human fibroblasts. The reactive intracellular structures comprised stress fibres, intermediate filaments, cell membrane associated, golgi complex, cytoplasm, cytoplasmic vesicles, mitochondria and nuclei. Of 45 stable clones derived by limiting dilution, 43 produced IgM antibodies and two IgG2b antibodies. Only one out of the 2,306 (0.04%) hybrids produced an autoantibody to the surface membrane of mouse thymocytes. These results show that B cells with reactivity towards different intracellular structures are present in the normal B cell repertoire whereas surface reactive B cells may be deleted or more profoundly suppressed or anergic and unable to form viable Ig producing hybridomas.