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By using most of the present CMB and LSS measurements and the BBN constraintson the primordial helium abundance, Y_p, we set bounds on the radiation contentof the Universe and neutrino properties. We consider lepton asymmetriccosmological models parametrized by the neutrino degeneracy parameter \xi_{\nu}and the variation of the relativistic degrees of freedom, \Delta N_{oth}^{eff},due to possible other physical processes that occurred between BBN andstructure formation epoch. We found that present CMB and LSS data constraintsthe neutrino degeneracy parameter at \xi_{\nu} \leq 0.722, implying a leptonasymmetry of the neutrino background {\cal L}_{\nu} \leq 0.614 (2-\sigma). Wealso found \Delta N^{eff}_{oth}=0.572^{+1.972}_{-1.780}, the contribution tothe effective number of relativistic neutrino speciesN^{eff}=3.058^{+1.971}_{-1.178} and a primordial helium abundanceY_p=0.249^{+0.014}_{-0.016} (2-\sigma errors). These results bring an importantimprovement over the similar ones obtained by using WMAP~1-year and older LSSdata or the WMAP~3-year data alone and the standard primordial helium abundancevalue Y_p=0.24, relaxing the stringent BBN constraint on the neutrinodegeneracy parameter (\xi_{\nu} \leq 0.07). We forecast that the CMBtemperature and polarization maps observed with high angular resolutions andsensitivity by the future Planck Mission will constraint the primordialprimordial helium abundance at Y_p=0.247 \pm 0.002 (2-\sigma errors) inagreement with the most stringent limits on Y_p given by the BBN and theneutrino degeneracy parameter at \xi_{\nu} \leq 0.280 (2-\sigma), not excludingthe possibility of larger lepton asymmetry. This work has been done on behalfof Planck-LFI activities.

Constraints on the lepton asymmetry and radiation energy density: Implications for PLANCK