CD4 and AIDS: As examples of HLA alleles associated to susceptibility and disease progression, HLA-B*27 and HLA-B*57 alleles were associated to slower progression to AIDS, control of viral load and high frequencies of CD4+ T cells (Migueles et al., 2000; Chopera et al., 2008); conversely, the HLA-B*35 allele was associated with rapid disease progression to AIDS (Tomiyama et al., 1997).