  We show that each 26D open bosonic Regge string scattering amplitude (RSSA)
can be expressed in terms of one single Appell function $F_1$ in the Regge
limit. This result enables us to derive infinite number of recurrence relations
among RSSA at arbitrary mass levels, which are conjectured to be related to the
known SL(5,C) dynamical symmetry of $F_1$. In addition, we show that these
recurrence relations in the Regge limit can be systematically solved so that
all RSSA can be expressed in terms of one amplitude. All these results are dual
to high energy symmetries of fixed angle string scattering amplitudes
discovered previously [4-8].
