Medical Definition of autoreactive
: produced by an organism and acting against its own cells or tissues <It has been presumed that autoreactive B cells, like normal B cells, accumulate in the follicles of lymphoid tissues after encountering antigen and begin to proliferate, producing high-affinity autoantibodies and forming germinal centers.—Yang-Xin Fu and Ursula Storb, Science, 20 Sept. 2002>
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