Haemophilus influenzae reside in tonsills and use IgD binding as an evasion strategy.

• Haemophilus influenzae (Hi) causes respiratory tract infections and is also considered as a commensal, particularly in pre-school children. Tonsils from patients (n=617) undergoing tonsillectomy due to chronical infection or hypertrophy were examined. We found that 51 % of tonsils were positive for Hi, and in 95 % of cases analysed in detail (n=39) Hi resided intracellularly in the core tonsillar tissue. Patients harboured several intracellular unique strains and the majority were non-typeable Hi (NTHi). Interestingly, the isolated NTHi bound soluble immunoglobulin (Ig) D at the constant heavy chain domain 1 as revealed by recombinant IgD/IgG chimeras. NTHi also interacted with B lymphocytes via the IgD B cell receptor resulting in internalization of bacteria, T-cell independent activation via Toll like receptor 9, and differentiation into non-NTHi specific IgM producing cells. Taken together, IgD-binding NTHi leads to an unspecific immune response and may support the bacteria to circumvent the host defense.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Infektionsmedicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Infectious Medicine (hsv//eng)

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