CD40 and pneumocystosis: Although the role of antibody opsonization is not well studied in pathogenic fungi, some studies have provided important insights including cases of PJP in patients receiving B-cell depletion (18), murine studies documenting the roles of CD40 on B cell immunity during pneumonia (19, 20), and observations that passive antibody treatment with anti-Pneumocystis antibody can provide PCP prophylaxis in rodents (21).