Defective natural killer cell anti-viral capacity in paediatric HBV infection.

Natural killer (NK) cells exhibit dysregulated effector function in adult chronic hepatitis B virus (HBV) infection (CHB), which may contribute to virus persistence. The role of NK cells in children infected perinatally with HBV is less studied. Access to a unique cohort enabled the cross-sectional evaluation of NK cell frequency, phenotype and function in HBV-infected children relative to uninfected children. We observed a selective defect in NK cell interferon (IFN)-γ production, with conserved cytolytic function, mirroring the functional dichotomy observed in adult infection. Reduced expression of NKp30 on NK cells suggests a role of impaired NK-dendritic cell (DC) cellular interactions as a potential mechanism leading to reduced IFN-γ production. The finding that NK cells are already defective in paediatric CHB, albeit less extensively than in adult CHB, has potential implications for the timing of anti-viral therapy aiming to restore immune control.

Suppurative iliac lymphadenitis masquerading as appendicitis in an HIV-infected patient.

An HIV-infected man presented with acute onset of right iliac fossa pain. Initial assessment of clinical and computed tomography findings suggested a diagnosis of appendicitis. A macroscopically normal appendix was removed. Further imaging performed postoperatively because of persistent symptoms showed a right iliac fossa mass; culture of pus aspirated from the mass grew group A beta-haemolytic Streptococcus confirming a diagnosis of suppurative iliac lymphadenitis.

Gastrointestinal histoplasmosis in an HIV-infected patient living in a non-endemic area.

SUMMARY: A 36-year-old HIV-infected man presented with non-specific gastrointestinal symptoms and weight loss. Biopsy of the duodenum and an intra-abdominal lymph node showed Histoplasma capsulatum. The diagnosis of histoplasmosis was delayed as the presentation was initially ascribed to intercurrent enteric pathogens and the patient's lifetime travel history was not obtained.

Hepatitis B infection: current concepts and future challenges.

Chronic hepatitis B (CHB) is a global health problem affecting more than 350 million people worldwide. Chronic carriage of HBV is related to the age when the infection occurs; the younger the age the higher the chronicity rate. Knowledge of the natural history of CHB is important for the management of the disease. The goal of hepatitis B treatment is to prevent cirrhosis, liver decompensation and hepatocellular carcinoma. In clinical practice, treatment response is determined by the suppression of serum HBV DNA levels. However, current antiviral therapies are usually unable to achieve sustained off-treatment responses and eradicate the infection. Impairment of immune responses including defective innate non-cytolytic antiviral function together with exhausted T cells and the tolerogenic liver environment may all contribute to the poor clinical response. A more comprehensive understanding of the immunological phases of CHB, potential triggers of liver flares and molecular mechanisms underlying viral persistence and immunopathology will help to tailor future therapeutic strategies. A synergistic approach of boosting the immune response of the host by specific immunotherapeutic interventions and effective viral load suppression will be needed to promote sustained viral clearance in chronic infection.