In light of this knowledge, we aimed to evaluate the level of differentiation of the immune system in relation to T-lymphocytes in ACS patients and its association with their periodontal disease status, to explore CD4 + Th/i and CD8 + Tc/s and macrophage concentrations in the gingival tissue samples of healthy individuals with periodontitis (no ACS + P), healthy individuals with gingivitis (no ACS + G), and ACS patients with periodontitis (ACS + P). The gene discussed is CD8A; the disease is periodontitis.