  The quark loop contribution to the reggeon-reggeon-gluon vertex is calculated
in QCD, where the reggeon is the reggeized gluon. Compared with the vertex in
the Born approximation, this contribution exhibits a new spin structure as well
as the gluon loop one. A remarkable but not complete cancellation between gluon
and quark contributions to this new spin structure takes place for the case of
three massless quark flavours.
