CD40LG and pneumocystosis: In addition, the suggestion that the IgM isotype has a predominant role in shaping the earliest steps in recognition and clearance of Pneumocystis infection both in mice (Rapaka et al., 2010) and in humans (Djawe et al., 2010; Tomás et al., 2016), not only support the role of antibodies in disease protection, but also highlights the idea that a serological test for PcP diagnosis is viable.