Full evolutionary models have been built to follow the phases of asymptotic giant branch evolution with mass loss for metal mass fractions from Z=0.0002 to Z=0.004. For the first time, we find that temperatures close to or even larger than 10^8 K are achieved at low Z; the full CNO cycle operates at the base of the envelope, the Oxygen abundance for the most metal-poor models of 4 and 5 solar masses is drastically reduced, and sodium and aluminum production by by proton capture on neon and magnesium can occur. These results may be relevant for the evolution of primordial massive globular clusters: we suggest that the low-mass stars may have been polluted at the surface by accretion from the gas that was lost from the evolving intermediate-mass stars at early ages.

14 pages, 6 figures