In this talk, I present a microscopic description of non-equilibrium spin transport through FM-AFM tunneling junctions. Employing path integral formulation of quantum statistical mechanics, one can derive formulas for spin torque, spin pumping and the power spectrum of spin current fluctuations at the junction in a single unified framework. Compared to FM-FM junctions, anti-damping-like torque is somewhat suppressed due to the spin degeneracy of electrons at different sublattice sites. Gilbert damping and noise magnetic field, which are equivalent to spin pumping and spin current fluctuations respectively, are explicitly shown to be dependent on the mutual orientation of FM and AFM. As an application, the AFM magnetic moment fluctuation induced by a steady voltage/temperature bias is computed.