  We compute scattering amplitudes of leading Regge trajectory states in open
superstring theories. Highest spin states at mass level n with spin s=n+1 for
bosons and s=n+1/2 for fermions are generated by particularly simple vertex
operators. Hence, the cubic couplings of bosons and fermions on the leading
Regge trajectory are given for arbitrary n. The same can be achieved for higher
point amplitudes, and this article focuses on four point level with one heavy
maximum spin state and three massless states in any bose-fermi combination,
putting particular emphasis on manifest cyclic symmetry. Except for the four
fermion coupling, all our results remain valid in any D<10 dimensional
compactification scenario, so they might become relevant at LHC in case of an
experimentally accessible low string scale. But even if not directly
observable, superstring amplitudes provide important clues on higher spin
dynamics and their consistent interactions in field theory.
