show Abstracthide AbstractThe interrelation of T and B-cell compartments at the T cell formation may be critical for balanced immune response. Primary B cell immunodeficiency (X-linked agammaglobulinemia, XLA) represents a model to explore the B cell impact on basic T cell features. We found the prominent alterations of the TCR repertoires of the naive regulatory T cells (nTreg) in XLA patients. At the transcriptome level, XLA nTreg showed increased expression of genes specific for APC and myeloid cells. Our findings indicate an active involvement of the B-cell population in nTreg homeostasis, revealing an intriguing new aspect in adaptive immunity.