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Medline ® Abstract for Reference 34

of 'Autoimmune lymphoproliferative syndrome (ALPS): Clinical features and diagnosis'

Defective anti-polysaccharide response and splenic marginal zone disorganization in ALPS patients.
Neven B, Bruneau J, Stolzenberg MC, Meyts I, Magerus-Chatinet A, Moens L, Lanzarotti N, Weller S, Amiranoff D, Florkin B, Bader-Meunier B, Leverger G, Ferster A, Chantrain C, Blanche S, Picard C, Molina TJ, Brousse N, Durandy A, Rizzi M, Bossuyt X, Fischer A, Rieux-Laucat F
Blood. 2014;124(10):1597.
Autoimmune lymphoproliferative syndrome (ALPS) caused by impaired FAS-mediated apoptosis of lymphocytes is characterized by lymphoproliferation, autoimmunity, but also an increased risk of invasive bacterial infection, notably following splenectomy. We surveyed a cohort of 100 ALPS patients (including 33 splenectomized) and found that 12 (10 splenectomized) had experienced 23 invasive bacterial infections mainly caused by Streptococcus pneumoniae. This vulnerability was associated with evidence of defective B-cell function characterized by low serum immunoglobulin (Ig) M, low IgM antibody production in response to S pneumoniae following nonconjugated immunization, and low blood memory B-cells counts (including marginal zone [MZ]B-cell counts). This immunodeficiency strongly correlated with intensity of lymphoproliferation. Spleen sections from 9 ALPS patients revealed double-negative T-cell (DN-T) infiltration of the MZ, which was depleted ofB cells. MZ in ALPS patients contained an abnormally thick layer of MAdCAM-1((+)) stromal cells and an excess of DN-Ts. DN-Ts were shown to express MAdCAM-1 ligand, theα4β7 integrin. These observations suggest that accumulating DN-Ts are trapped within stromal cell meshwork and interfere with correct localization of MZ B cells. Similar observations were made in spleens of fas-deficient mice. Our data revealed an unexpected mechanism by which ALPS results in anti-polysaccharide IgM antibody production-specific defect. Splenectomy should be avoided.
Unitéd'immuno-hématologie pédiatrique, Hôpital Necker-Enfant Malades, Assistance Publique des Hôpitaux de Paris, Paris, France; Développement normal et pathologique du système immunitaire, UnitéINSERM U768, UniversitéDescartes, Sorbonne Paris Cité, Institut IMAGINE, Paris, France;