In mucosal defense, both innate and adaptive lymphocytes play key roles in containing commensal microbial populations and protecting against pathogen invasion. For a study, researchers examined the mucosal immunity in patients with severe combined immunodeficiency (SCID) who were getting hematopoietic stem cell transplantation (HSCT) with or without myeloablation.
They verified that pretransplant training influenced innate (natural killer and innate lymphoid cells) and adaptive (B and T cells) lymphocyte reconstitution in the patients with SCID, and they showed that it extended to the production of T helper 2 and type 2 cytotoxic T cells. Using an integrated method to evaluate nasopharyngeal immunity, they discovered a local mucosal impairment in type 2 cytokines, mucus production, and a selective local immunoglobulin A (IgA) deficiency in HSCT-treated SCID patients with IL2RG/GC or JAK3 genetic abnormalities.
The patients had less IgA-coated nasopharyngeal bacteria and microbial dysbiosis with higher pathobiont carriage. Interestingly, in GC/JAK3 patients, intravenous immunoglobulin replacement treatment can partially correct nasopharyngeal immunoglobulin profiles and restore microbial communities. The findings implied that type 2 immunity and/or local IgA antibody production may have a nonredundant role in the maintenance of nasopharyngeal microbial homeostasis and mucosal barrier function.
Reference:ashpublications.org/blood/article/139/17/2585/484002/Defects-in-mucosal-immunity-and-nasopharyngeal
