Immunoglobulin (Ig) replacement therapy dramatically changed the clinical course of primary hypogammaglobulinemias, significantly reducing the incidence of infectious events. Over the last 2 decades its use has been extended to secondary antibody deficiencies, particularly those related to hematological disorders as lymphoproliferative diseases (LPDs) and multiple myeloma. In these malignancies, hypogammaglobulinemia can be an intrinsic aspect of the disease or follow chemo-immunotherapy regimens, including anti-CD20 treatment. Other than in LPDs the broadening use of immunotherapy (e.g. rituximab) and immune suppressive therapy (steroids, sulfasalazine, mycophenolate mophetil) has extended the occurrence of iatrogenic hypogammaglobulinemia. In particular, in both autoimmune diseases and solid organ transplantation Ig replacement therapy has been shown to reduce the rate of infectious events. Here, we review the existing literature about Ig replacement therapy in secondary hypogammaglobulinemia, with special regard for subcutaneous administration route, a safe, effective and well-tolerated treatment approach, currently well established in primary immunodeficiencies and secondary hypogammaglobulinemias.

In idiopathic pulmonary fibrosis (IPF), the fibroblast focus is a key histological feature representing active fibroproliferation. On standard 2D pathologic examination, fibroblast foci are considered small, distinct lesions, although they have been proposed to form a highly interconnected reticulum as the leading edge of a “wave” of fibrosis. Here, we characterized fibroblast focus morphology and interrelationships in 3D using an integrated micro-CT and histological methodology. In 3D, fibroblast foci were morphologically complex structures, with large variations in shape and volume (range, 1.3 × 10 ⁴ to 9.9 × 10 ⁷ μm ³ ). Within each tissue sample numerous multiform foci were present, ranging from a minimum of 0.9 per mm ³ of lung tissue to a maximum of 11.1 per mm ³ of lung tissue. Each focus was an independent structure, and no interconnections were observed. Together, our data indicate that in 3D fibroblast foci form a constellation of heterogeneous structures with large variations in shape and volume, suggesting previously unrecognized plasticity. No evidence of interconnectivity was identified, consistent with the concept that foci represent discrete sites of lung injury and repair.

Lacking protective antibodies, patients with primary antibody deficiencies (PADs) experience frequent respiratory tract infections, leading to chronic pulmonary damage. Macrolide prophylaxis has proved effective in patients with chronic respiratory diseases. We aimed to test the efficacy and safety of orally administered low-dose azithromycin prophylaxis in patients with PADs. We designed a 3-year, double-blind, placebo-controlled, randomized clinical trial to test whether oral azithromycin (250 mg administered once daily 3 times a week for 2 years) would reduce respiratory exacerbations in patients with PADs and chronic infection-related pulmonary diseases. The primary end point was the number of annual respiratory exacerbations. Secondary end points included time to first exacerbation, additional antibiotic courses, number of hospitalizations, and safety. Eighty-nine patients received azithromycin (n = 44) or placebo (n = 45). The number of exacerbations was 3.6 (95% CI, 2.5-4.7) per patient-year in the azithromycin arm and 5.2 (95% CI, 4.1-6.4) per patient-year in the placebo arm (P = .02). In the azithromycin group the hazard risk for having an acute exacerbation was 0.5 (95% CI, 0.3-0.9; P = .03), and the hazard risk for hospitalization was 0.5 (95% CI, 0.2-1.1; P = .04). The rate of additional antibiotic treatment per patient-year was 2.3 (95% CI, 2.1-3.4) in the intervention group and 3.6 (95% CI, 2.9-4.3) in the placebo group (P = .004). Haemophilus influenzae and Streptococcus pneumoniae were the prevalent isolates, and they were not susceptible to macrolides in 25% of patients of both arms. Azithromycin's safety profile was comparable with that of placebo. The study reached the main outcome centered on the reduction of exacerbation episodes per patient-year, with a consequent reduction in additional courses of antibiotics and risk of hospitalization.