Haemophilus influenzae resides in tonsils and uses immunoglobulin D binding as an evasion strategy.
Haemophilus influenzae (Hi) causes respiratory tract infections and is also considered to be a commensal, particularly in preschool children. Tonsils from patients (n = 617) undergoing tonsillectomy due to chronic infection or hypertrophy were examined. We found that 51% of tonsils were positive for Hi, and in 95% of cases analyzed in detail (n = 39) Hi resided intracellularly in the core tonsillar tissue. Patients harbored several intracellular unique strains and the majority were nontypeable 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.
Medical Microbiology, Department of Laboratory Medicine Malmö, Lund University, Malmö
Kalpana
K
Singh
Therése
T
Nordström
Matthias
M
Mörgelin
Marta
M
Brant
Lars-Olaf
LO
Cardell
Kristian
K
Riesbeck
D000293:Adolescent; D001402:B-Lymphocytes / Q000276:immunology; D002648:Child; D005260:Female; D006192:Haemophilus Infections / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D057131:Immune Evasion; D007072:Immunoglobulin D / Q000276:immunology* / Q000378:metabolism; D008297:Male; D014066:Palatine Tonsil / Q000382:microbiology*; D013548:Sweden / Q000453:epidemiology; D051217:Toll-Like Receptor 9 / Q000276:immunology; D055815:Young Adult
D007072:Immunoglobulin D; C495371:TLR9 protein, human; D051217:Toll-Like Receptor 9
B cells; Haemophilus influenzae; immunoglobulin D