How is an allergic reaction similar to the rejection of a transplanted organ?

An allergic reaction is similar to the rejections of a transplanted organ because just like allergies your immune system turns on itself,which would cause effects like itchy watery eyes,itchy throat,sweating,hard to breath,ext.An organism with white blood cells are rejected from someone with a inactive immune system.Basically they are similar because the body rejects both of them and it can cause some health issues if not treated right away.