  In the colliding wind region of early-type binaries, electrons can be
accelerated up to relativistic energies displaying power-law spectra, as
demonstrated by the detection of non-thermal radio emission from several WR+OB
systems. The particle acceleration region, located between the stars, is
exposed to strong photon fields in such a way that inverse Compton cooling of
the electrons could result in a substantial high-energy non-thermal flux. In
particular cases, the ratio of the energy densities of magnetic to photon
fields in the colliding wind region will determine whether a given source can
produce or not significant gamma-ray emission. We present here a study of the
binaries WR 140, WR 146, and WR 147 in the light of recent radio and gamma-ray
observations. We show that with reasonable assumptions for the magnetic field
strength WR 140 can produce the gamma-ray flux from the EGRET source 3EG
J2022+4317. WR 146 and WR 147 are below the detection threshold, but
forthcoming instruments like INTEGRAL and GLAST could detect non-thermal
emission from them.
