Relationship between the synthesis of autoimmune antibodies and the formation of clusters of B,T and APC cells during the syngeneic mixed lymphocyte reaction in BALB/c and NZB mice: A technique for isolation of the spleen autoimmune compartment of non-immunized pathogen-free mice

Cells from the spleens of non-immunized mice were cultured in horizontal tubes, rotating very slowly around their long axis. Under these conditions, the flux speed gradient of the cell suspension near the tube walls greatly increased the chances of cells coming into contact with one another. Mixed clusters of B, T and APC cells were soon found adhering firmly to the walls of the tube; cluster formation leveled off after about 3 h. The clustered cells were easily separated from those remaining in suspension and constituted a particular cell compartment comprising a maximum of 20–30 % of the total.B cells from this compartment, cultured in complete medium for 48 h, almost exclusively produced IgM antibodies. Antibodies reacting with self antigens were so numerous in the culture medium that it is likely all IgM were self antibodies.That the clusters obtained under these conditions constituted a compartment of autoimmune cells is supported by previous work which showed that 20–30 % of spleen cells secrete IgM antibodies almost exclusively.Cluster formation as a function of age was compared in NZB mice which are used as a model of lupus erythematosus, and in BALB/c mice which never manifest self-immune pathology. The number of cells found in clusters per whole spleen increased exponentially with age in NZB mice and linearly in BALB/c mice. The production of autoimmune antibodies as a function of age also increased exponentially for NZB mice and linearly in BALB/c mice, which provides further striking support for the hypothesis that the clusters formed constitute the autoimmune comportment.