Although elevation of serum levels of KL-6 and SP-A are reported in PCP, while elevation of the serum (1→3) β-D-glucan (β-D-glucan) level has been reported as a marker of PCP [12,13], whether these markers are affected by P. jirovecii colonization has not yet been investigated in IP patients. Here, MUC1 is linked to pneumocystosis.