How is transversity related to helicity for quarks and antiquarks inside the proton?

We consider the quark and antiquark transversity distributions inside a polarized proton and we study how they are expected to be related to the corresponding helicity distributions, both in sign and magnitude. Our considerations lead to simple predictions in good agreement with their first determination for light quarks from experimental data. We also give our predictions for the light antiquarks transversity distributions, so far unknown.