ITGB2 and periodontitis: Lastly, the P vs. H comparison, which evaluated the association with periodontitis, the RT-qPCR from circulating lymphocytes and monocytes confirmed that the HLADRB4 and ITGB2 (integrin subunit beta 2) genes were upregulated in H, while the IGHDL-P (immunoglobulin heavy constant gamma 3) gene was downregulated in H (Fig. 6B,E).