Abstracts (complete list) - Wissenschaft Online

Baerbel Keller, Mirzokhid Rakhmanov, Sylvia Gutenberger, Sigune Goldacker, Dirk
Holzinger, Elisabeth Nikolopoulus, Paul Fisch, Hermann Eibel, Hans-Hartmut Peter,
Klaus Warnatz
CD21low B Cells Represent a Polyclonally Activated B Cell
Population Exposed to Type I Interferons
Most patients with common variable immunodeficiency (CVID) exhibit a severely
disturbed homeostasis of the circulating B cell pool. About 10% of these patients are
characterized by the expansion of B cells with an unusually low expression of CD21.
These CD21lowCD38low B cells exhibit an activated phenotype with increased cell size
and elevated levels of CD86. Spectrotyping of sorted cells identified a polyclonal origin
of CD21low B cells. A similar expansion of CD21low B cells in SLE as well as HIV
infected patients suggested a potential role of type I interferon stimulation. Gene
expression analysis for MxA, OAS1 and IFIT1 of FACS sorted CD21low B cells versus
naive B cells of HD and CVID patients confirmed the interferon signature in CD21low B
cells. Since HHV8 was suggested as a possible pathogen in a subgroup of CVID patients
we tested our patients with expanded CD21low B cells and granulomatous disease, but
could not confirm a role of HHV8 in our cohort. Currently we are investigating polyclonal
activation of B cells via different Toll like receptors as a possible source of CD21low B
cell differentiation.