Revisiting the B-cell compartment in mouse and humans: more than one B-cell subset exists in the marginal zone and beyond.

International audienceABSTRACT: The immunological roles of B-cells are being revealed as increasingly complex by functions that are largely beyond their commitment to differentiate into plasma cells and produce antibodies, the key molecular protagonists of innate immunity, and also by their compartmentalisation, a more recently acknowledged property of this immune cell category. For decades, B-cells have been recognised by their expression of an immunoglobulin that serves the function of an antigen receptor, which mediates intracellular signalling assisted by companion molecules. As such, B-cells were considered simple in their functioning compared to the other major type of immune cell, the T-lymphocytes, which comprise conventional T-lymphocyte subsets with seminal roles in homeostasis and pathology, and non-conventional T-lymphocyte subsets for which increasing knowledge is accumulating. Since the discovery that the B-cell family included two distinct categories - the non-conventional, or extrafollicular, B1 cells, that have mainly been characterised in the mouse; and the conventional, or lymph node type, B2 cells - plus the detailed description of the main B-cell regulator, FcγRIIb, and the function of CD40+ antigen presenting cells as committed/memory B-cells, progress in B-cell physiology has been slower than in other areas of immunology. Cellular and molecular tools have enabled the revival of innate immunity by allowing almost all aspects of cellular immunology to be re-visited. As such, B-cells were found to express "Pathogen Recognition Receptors" such as TLRs, and use them in concert with B-cell signalling during innate and adaptive immunity. An era of B-cell phenotypic and functional analysis thus began that encompassed the study of B-cell microanatomy principally in the lymph nodes, spleen and mucosae. The novel discovery of the differential localisation of B-cells with distinct phenotypes and functions revealed the compartmentalisation of B-cells. This review thus aims to describe novel findings regarding the B-cell compartments found in the mouse as a model organism, and in human physiology and pathology. It must be emphasised that some differences are noticeable between the mouse and human systems, thus increasing the complexity of B-cell compartmentalisation. Special attention will be given to the (lymph node and spleen) marginal zones, which represent major crossroads for B-cell types and functions and a challenge for understanding better the role of B-cell specificities in innate and adaptive immunology

An unusual case of chronic meningitis

BACKGROUND: Chronic meningitis is defined as symptoms and signs of meningeal inflammation and persisting cerebrospinal fluid abnormalities such as elevated protein level and pleocytosis for at least one month. CASE PRESENTATION: A 62-year-old woman, of unremarkable past medical history, was admitted to hospital for investigation of a four-week history of vomiting, malaise an associated hyponatraemia. She had a low-grade pyrexia with normal inflammatory markers. A CT brain was unremarkable and a contrast MRI brain revealed sub-acute infarction of the right frontal cortex but with no evidence of meningeal enhancement. Due to increasing confusion and patient clinical deterioration a lumbar puncture was performed at 17 days post admission. This revealed gram-negative coccobacilli in the CSF, which was identified as Neisseria meningitidis group B. The patient made a dramatic recovery with high-dose intravenous ceftriaxone antibiotic therapy for meningococcal meningitis. CONCLUSIONS: 1) Chronic bacterial meningitis may present highly atypically, particularly in the older adult. 2) There may be an absent or reduced febrile response, without a rise in inflammatory markers, despite a very unwell patient. 3) Early lumbar puncture is to be encouraged as it is essential to confirm the diagnosis.4) Despite a delayed diagnosis appropriate antibiotic therapy can still lead to a good outcome

Use and efficacy of pneumococcal vaccine in patients with Hodgkin disease

Fulminant bacterial sepsis has been described in patients with Hodgkin disease who have undergone splenectomy for staging purposes. The organisms commonly associated with sepsis in this setting include Streptococcus pneumoniae and Haemophilus influenzae. Polyvalent pneumococcal vaccine (Merck) has recently been licensed and has been suggested for use in patients with Hodgkin disease who are at risk for postsplenectomy sepsis. We administered 14-valent pneumococcal vaccine to 24 patients with Hodgkin disease and 24 normal controls, and measured antibody response to 13 antigens at time of immunization and at 3 wk and 3 mo following immunization. Our results indicate that patients who have been previously treated for Hodgkin disease, with chemotherapy, radiotherapy, or both, have severe impairment of antibody response. Untreated patients, however, respond in a manner similar to normal controls.</jats:p

Use and efficacy of pneumococcal vaccine in patients with Hodgkin disease

Abstract Fulminant bacterial sepsis has been described in patients with Hodgkin disease who have undergone splenectomy for staging purposes. The organisms commonly associated with sepsis in this setting include Streptococcus pneumoniae and Haemophilus influenzae. Polyvalent pneumococcal vaccine (Merck) has recently been licensed and has been suggested for use in patients with Hodgkin disease who are at risk for postsplenectomy sepsis. We administered 14-valent pneumococcal vaccine to 24 patients with Hodgkin disease and 24 normal controls, and measured antibody response to 13 antigens at time of immunization and at 3 wk and 3 mo following immunization. Our results indicate that patients who have been previously treated for Hodgkin disease, with chemotherapy, radiotherapy, or both, have severe impairment of antibody response. Untreated patients, however, respond in a manner similar to normal controls.</jats:p