ICOS and idiopathic pulmonary arterial hypertension: Since the role of γδT-cells in autoimmune disease is to help B-cells to produce autoantibodies through costimulatory molecules like CD40L, inducible T-cell co-stimulator (ICOS), and CD28 and the release of pro-inflammatory cytokines (Rampoldi et al., 2020), it is tempting to assume that pDCs provide a link in the recruitment and activation of γδT-cells that, in turn, shape B-cell autoimmunity of IPAH (Figure 4).