We performed a retrospective genome-wide association study in HIV-infected individuals who were treated with dendritic cell-based immunotherapy in clinical trials performed by two research groups (Spain and Brazil). We aimed to identify host genetic variants influencing treatment response. The Illumina Human Core Exome 12 v 1.0 Bead Chip with over 250,000 markers was used to analyze genetic factors affecting treatment response. Additionally, we performed a meta-analysis of the results obtained from Spanish and Brazilian patients. We identified a genetic variation (rs7935564 G allele) in TRIM22 gene, which encodes TRIM22 protein acting like a HIV restriction factor, as being associated with good response to dendritic cell-based immunotherapy. We then verified the impact of TRIM22 rs7935564 SNP in susceptibility to HIV infection and disease progression by assessing the influence of biogeographic ancestry in the distribution of allelic and genotype frequencies in three populations from Italy, Brazil and Zambia. TRIM22 rs7935564 genotyping indicated association of G rs7935564 allele with long-term non-progression of HIV disease in Italian patients, thus corroborating our hypothesis that it is involved as a restriction factor in dendritic cell-based immunotherapy response. TRIM22 rs7935564 polymorphism was associated with good response to dendritic cell-based immunotherapy. We hypothesize that in selecting patients for treatment, there is a possible bias related to the natural presence of restriction factors that are genetically determined and could influence final outcome of therapy.