INFLUENCE OF VIRAL-INFECTION ON ANTIERYTHROCYTE AUTOANTIBODY RESPONSEAFTER IMMUNIZATION OF MICE WITH RAT RED-BLOOD-CELLS

Natural or deliberate activation of the immune system of pathogen-free mice markedly affected their response to an autoimmune-inducing stimu lus. Specifically, mice immunized with rat red blood cells were found to make antibodies reactive with both rat and mouse erythrocytes. Anim als housed for an extended period in a conventional environment develo ped an autoimmune response twice as fast as those kept in isolators. I n an attempt to emulate this effect, mice kept in a sterile environmen t were infected with a potent polyclonal activator of B lymphocytes, l actate dehydrogenase-elevating virus, at the same time as they were in oculated with rat erythrocytes. Whereas uninfected animals developed a progressively increasing autoantibody titer, infected mice quickly at tained high anti-erythrocyte autoantibody titers that remained rather constant. Contrary to circulating autoantibodies, bound anti-erythrocy te antibodies decreased with time. Virus infection enhanced all the Ig G subclass responses, with the exception of IgG1, to both rat and mous e erythrocytes. None of the modifications of the autoimmune responses resulted in anemia.