Splenic T-bet+ B cells exhibit stem-like features and constitutively generate antibody-secreting cells

T-bet-expressing B cells (a.k.a. Age-Associated B cells or atypical B cells) directly contribute to antiviral and autoimmune responses and thus represent a promising target for immunomodulatory therapies. T-bet+ memory B cells (MBCs) form and persist long term in the spleen as a resident subset; however, the functional role of this tissue-based population and mechanisms for its maintenance are poorly understood. Here, we use T-bet reporter and fate mapping mouse models to investigate the homeostasis and fate of T-bet+ B cell subsets. We identified an elevated turnover rate of T-bet+ MBCs, with ~1.5% of the population labeling with BrdU per day and 5–10% of T-bet+ MBCs in cell cycle (G1 or S) at any given time. T-bet+ MBCs also displayed resistance to sub-lethal irradiation. Fate mapping and adoptive transfer studies demonstrate that splenic T-bethigh B cells (Tbet++ CD11c+) spontaneously give rise to T-betlow (Tbet+ CD11c−) and ultimately a variety of effector B cell subsets, including GCB-like cells, plasma cells, and T-bet− memory-like B cells, absent exogenous challenge or stimulation. T-bet+ MBCs preferentially give rise to short-lived (CD138+ B220+) versus long-lived (CD138+ B220−) bone marrow and splenic plasma cells, and adoptively transferred T-bet+ MBCs are sufficient to generate plasma IgG2c titers in IgG2a-haptolype naïve recipients. Considering their long-term maintenance in the spleen, these findings suggest T-bet+ MBCs represent a self-renewing, stem-like pool that contribute to the maintenance of antibody titers by constitutive differentiation into antibody-secreting cells.

IgA Plasma Cells Are Long-Lived Residents of Gut and Bone Marrow That Express Isotype- and Tissue-Specific Gene Expression Patterns

Antibody secreting plasma cells are made in response to a variety of pathogenic and commensal microbes. While all plasma cells express a core gene transcription program that allows them to secrete large quantities of immunoglobulin, unique transcriptional profiles are linked to plasma cells expressing different antibody isotypes. IgA expressing plasma cells are generally thought of as short-lived in mucosal tissues and they have been understudied in systemic sites like the bone marrow. We find that IgA+ plasma cells in both the small intestine lamina propria and the bone marrow are long-lived and transcriptionally related compared to IgG and IgM expressing bone marrow plasma cells. IgA+ plasma cells show signs of shared clonality between the gut and bone marrow, but they do not recirculate at a significant rate and are found within bone marrow plasma cells niches. These data suggest that systemic and mucosal IgA+ plasma cells are from a common source, but they do not migrate between tissues. However, comparison of the plasma cells from the small intestine lamina propria to the bone marrow demonstrate a tissue specific gene transcription program. Understanding how these tissue specific gene networks are regulated in plasma cells could lead to increased understanding of the induction of mucosal versus systemic antibody responses and improve vaccine design.

The Transcription Factor T-bet Resolves Memory B Cell Subsets with Distinct Tissue Distributions and Antibody Specificities in Mice and Humans

B cell subsets expressing the transcription factor T-bet are associated with humoral immune responses and autoimmunity. Here, we examined the anatomic distribution, clonal relationships, and functional properties of T-bet⁺ and T-bet^- memory B cells (MBCs) in the context of the influenza-specific immune response. In mice, both T-bet^- and T-bet⁺ hemagglutinin (HA)-specific B cells arose in germinal centers, acquired memory B cell markers, and persisted indefinitely. Lineage tracing and IgH repertoire analyses revealed minimal interconversion between T-bet^- and T-bet⁺ MBCs, and parabionts showed differential tissue residency and recirculation properties. T-bet⁺ MBCs could be subdivided into recirculating T-bet^lo MBCs and spleen-resident T-bet^hi MBCs. Human MBCs displayed similar features. Conditional gene deletion studies revealed that T-bet expression in B cells was required for nearly all HA stalk-specific IgG2c antibodies and for durable neutralizing titers to influenza. Thus, T-bet expression distinguishes MBC subsets that have profoundly different homing, residency, and functional properties, and mediate distinct aspects of humoral immune memory.

Effectiveness of altering serum cholesterol levels without drugs

Drug therapy with statins and other agents can result in dramatic lipid-lowering effects. Despite the wealth of data supporting the beneficial effects of pharmacologic therapy on cardiovascular risk, patients often express a desire to accomplish similar goals with diet alone. And, except for patients with extreme cholesterol elevations, consensus panels all promote dietary therapy as an initial step in the treatment of hyperlipidemia. This review examines a variety of dietary strategies designed to lower lipid levels, including the American Heart Association diet, the Ornish diet, the Mediterranean diet, exercise, phytosterols, fiber, soy products, and fish oil. Though the declines in low-density lipoprotein cholesterol levels with these methods range from 0% to 37%, cardiovascular risk may be more significantly impacted than would be predicted from these changes alone. Significant benefits can be reaped from nonpharmacologic measures.

Dental fellowships in developmental disabilities help broaden care of disabled

Continuation of the national trend toward deinstitutionalization and community placement for persons with developmental disabilities, physical handicaps and other medical problems will mean increased demand for dentists trained to care for this segment of the population. The New York State Office of Mental Retardation and Developmental Disabilities now offers dental fellowships in developmental disabilities to help fill the learning gap.

Immunochemical differences between glucocorticoid receptors from corticoid-sensitive and -resistant malignant lymphocytes

We have explored the possibility of using antibodies against purified rat liver glucocorticoid receptors to study the immunochemical properties of glucocorticoid receptors from murine and human malignant lymphocytes. For this purpose, purified immune immunoglobulin G was covalently linked to Sepharose CL-4B. We then examined the ability of the affinity gel to recognize cytosolic [3H]triamcinolone acetonide-receptor complexes from the corticoid-sensitive (CS) and -resistant strains of mouse lymphoma P1798, from CS lymphocytes of patients with chronic lymphatic leukemia, and from a CS clone of human leukemic lymphoblasts in tissue culture (CH6). Mouse thymus was used as a source of glucocorticoid receptor from normal CS lymphocytes. Whereas the immunoaffinity column retained 70 to 84% of the 58- to 62-A (Stokes radius) [3H]triamcinolone acetonide-receptor complexes characteristic of the CS mouse and human lymphocytes, it failed to recognize the 27- to 28-A (Stokes radius) glucocorticoid receptor present in corticoid-resistant mouse lymphoma P1798 cells. Therefore, under appropriate experimental conditions, it was possible to demonstrate cross-reactivity between the antiserum against rat liver glucocorticoid receptor and the 58- to 62-A (Stokes radius) glucocorticoid receptor from species as diverse as mouse and humans.

Intensive therapy for hepatic coma

Of 45 patients observed in the ICU with severe acute hepatic insufficiency, 15 patients were in hepatic coma. All patients received combined treatment consisting of standard conservative methods (drug therapy) and surgical methods for temporary support of liver function (hemodialysis, exchange blood transfusion, pig liver perfusion). Intensive therapy which began during the early phase of hepatic coma enabled us to bring six patients out of the coma, four of whom completely recovered. These studies showed that of the diseases causing hepatic coma, the worst results were obtained with viral hepatitis. This may be explained both by the extensive liver damage and marked metabolic disturbances, which led to failure of other vital organs and systems. At present, the combined therapy contributes to a greater percentage of recovery of patients with hepatic failure and coma.

A simple test to determine the need for occlusal treatment

This report has described simple confirmation tests which show the direct relationship between a patient's occlusal interferences and his neuromuscular or temporomandibular articulation dysfunction. These tests are simple to perform, take only a few minutes, and aid in confirming the need for occlusal therapy.

Chronic myofascial pain-dysfunction syndrome with chest pain

A patient with a myofascial pain-dysfunction (MPD) syndrome with pain radiating into the chest has been described. A direct relationship between a dental malocclusion and the chest pain was confirmed by tests. The patient was treated for MPD syndrome related to the malocclusion, and the chest pain symptoms were relieved. This report demonstrates the need for the dentist to consider not only the muscles of mastication in the management of problems of the neuromuscular apparatus but also the delicate balance which exists between the masticatory apparatus and the postural muscles of the head and neck.

Aspects of anaesthetic management of heterologous extracorporeal hepatic support in patients with acute liver failure

Some anaesthetic aspects of heterologous extracorporeal hepatic support for patients with acute liver failure have been investigated in animals and men. Two types of anaesthesia during hepatectomy in pigs were performed in 20 experiments divided into two groups. A convenient anaesthetic technique was found to be the combined use of neuroleptanalgesics, gamma-OH, small doses of thiopental sodium and nitrous oxide--oxygen mixture. The necessity for care in the procedure of temporary liver support for 'poor-risk' patients is outlined. A minimal use of drugs which are metabolized by the liver, and avoidance of potent analgesics, narcotics, hypotension and hypoxia are the main principles for safe extracorporeal hepatic assistance to critically ill patients.