CTLA4 and periodontitis: In periodontitis, an increase in the expression of CTLA4 on CD4+ T-cells has been found related to the presence of periodontitis and, more recently, the study of these IR has specifically focused on the context of the relationship of possible polymorphisms of the gene that encodes it with susceptibility to specific forms of periodontitis in different populations (123–125) (Figure 1E).