Increased proportions of γδ T lymphocytes in atypical SCID associate with disease manifestations.

Abstract Severe combined immunodeficiencies (SCID) comprise a group of genetic diseases characterized by abrogated development of T lymphocytes. In some case reports of atypical SCID patients elevated proportions of γδ T lymphocytes have been reported. However, it is unknown whether these γδ T cells modulate or reflect the patient's clinical phenotype. We investigated the frequency of elevated γδ T cell proportions and associations with clinical disease manifestations in a cohort of 76 atypical SCID patients. Increased proportions of γδ T lymphocytes were present in approximately 60% of these patients. Furthermore, we identified positive correlations between elevated proportions of γδ T cells and the occurrence of CMV infections and autoimmune cytopenias. We discuss that CMV infections might trigger an expansion of γδ T lymphocytes, which could drive the development of autoimmune cytopenias. We advocate that atypical SCID patients should be screened for elevated proportions of γδ T lymphocytes, CMV infection and autoimmune cytopenias. Highlights • Elevated proportions of γδ T lymphocytes are frequently present in atypical SCID patients. • Elevated proportions of γδ T lymphocytes associate with CMV infection and autoimmune cytopenias. • γδ T cell proportions do not associate with other autoimmune or infectious diseases. [ABSTRACT FROM AUTHOR]