All possible interactions of a point particle with background electromagnet
ic, gravitational and higher-spin fields are considered in the two-time phy
sics worldline formalism in (d,2) dimensions. This system has a counterpart
in a recent formulation of two-time physics in noncommutative field theory
with local Sp(2) symmetry. In either the worldline or field theory formula
tion, a general Sp(2) algebraic constraint governs the interactions, and de
termines the equations that the background fields of any spin must obey. Th
e constraints are solved in the classical worldline formalism ((h) over bar
-->0 limit) as well as in the field theory formalism (all powers of (h) ove
r bar). The solution in both cases coincide for a certain 2T to 1T holograp
hic image which describes a relativistic particle interacting with backgrou
nd fields of any spin in (d-1, 1) dimensions. Two disconnected branches of
solutions exist, which seem to have a correspondence as massless states in
string theory, one containing low spins in the zero Regge slope limit, and
the other containing high spins in the infinite Regge slope limit.