Figure 1.

Lymphocytes are a diverse set of immune cells within adaptive immunity. Lymphocytes are characterized by specific receptor markers (illustrated in cellular representative images) needed for activation and can regulate cardiac fibrosis that occurs through varying mechanisms. Although some subsets have demonstrated direct actions on cardiac fibroblast through secretion of growth factors, other lymphocytes have demonstrated more of an indirect role by regulating matrix metalloproteases and innate immune cells including macrophages. In turn, fibroblasts can modulate lymphocyte recruitment and phenotypes. ECM, extracellular matrix; MMP, matrix metalloproteinase; TGF-β, tissue growth factor-β.