Production and functional properties of eosinophils from bone marrow cultures

Bone marrow cultures have been established from mice infected with Mesocestoides corti and undergoing parasitic eosinophilia. In the absence of added conditioned medium, eosinophil differentiation ceases, and eosinophils are undetectable by 7 days, whereas neutrophil production continues over several weeks as with normal bone marrow. Eosinophil production can be induced by adding pokeweed mitogen-stimulated spleen supernatants (MSSS) or specific antigen-stimulated spleen supernatants (ASSS) produced from-spleen cells of M. corti-infected mice. In contrast to the continuous production of neutrophils, eosinophil production is transient, suggesting that there is no continued production of eosinophil progenitor cells in these cultures. More eosinophils are produced when MSSS is added at the initiation of cultures, compared to after a delay of 2 weeks, and establishing the cultures at 33 degrees C does not appear to enhance eosinophil production. The eosinophils produced are shown to express the eosinophil differentiation antigen defined by monoclonal antibody NIMP-R13, they produce eosinophil peroxidase in similar amounts to eosinophils taken from mice. They show normal phagocytic activity of antibody-coated erythrocytes and lyse red cells coated with antibodies of IgG1, IgG2a, IgG2b, but not IgM isotypes.