Sylvie Amu

Folate, vitamin B12, and homocysteine levels in South Asian women with growth- retarded fetuses

Objective.u2002 To investigate whether intrauterine growth retardation (IUGR) and preterm delivery in a poor population of South Asia was associated with altered maternal and fetal levels of folate, vitamin B12, and homocysteine.

The Human Immunomodulatory CD25+ B Cell Population belongs to the Memory B Cell Pool

We have shown that human CD20+25+ B cells display immunomodulatory properties. The aim of this study was to investigate if CD25+ B cells are found within the CD27 memory B cell population, and to analyse pattern of their cytokine production.

Short- and long-term effects of anti-CD20 treatment on B cell ontogeny in bone marrow of patients with rheumatoid arthritis

IntroductionIn the present study we evaluated changes in the B cell phenotype in peripheral blood and bone marrow (BM) of patients with rheumatoid arthritis (RA) following anti-CD20 treatment using rituximab.MethodsBlood and BM samples were obtained from 37 patients with RA prior to rituximab treatment. Ten of these patients were resampled 1 month following rituximab, 14 patients after 3 months and the remaining 13 patients were included in the long-term follow up. B cell populations were characterized by CD27/IgD/CD38/CD24 expression.ResultsOne and three months following rituximab BM retained up to 30% of B cells while circulation was totally depleted of B cells. Analysis of the remaining BM B cells showed prevalence of immature and/or transitional B cells (CD38++CD24++) and CD27+IgD- memory cells, while IgD+ cells were completely depleted. A significant reduction of CD27+ cells in BM and in circulation was observed long after rituximab treatment (mean 22 months), while levels of naive B cells in BM and in circulation were increased. The levels of rheumatoid factor decline after rituximab treatment but returned to baseline levels at the time of retreatment.ConclusionsAnti-CD20 treatment achieves a depletion of IgD+ B cells shortly after the treatment. At the long term follow up, a reduction of CD27+ B cells was observed in blood and BM. The prolonged inability to up-regulate CD27 may inhibit the renewal of memory B cells. This reduction of CD27+ B cells does not prevent autoantibody production suggesting that mechanisms regulating the formation of auto reactive clones are not disrupted by rituximab.

Vaccination response to protein and carbohydrate antigens in patients with rheumatoid arthritis after rituximab treatment

IntroductionRheumatoid arthritis (RA) is frequently complicated with infections. The aim of our study was to evaluate vaccination response in patients with RA after B-cell depletion by using rituximab.MethodsInfluenza (Afluria) and pneumococcal polysaccharides (Pneumo23) vaccines were given 6 months after rituximab (post-RTX group, n = 11) or 6 days before rituximab treatment (pre-RTX group; n = 8). RA patients never exposed to RTX composed the control group (n = 10). Vaccine-specific cellular responses were evaluated on day 6 after vaccination, and vaccine-specific humoral responses, on day 21.ResultsOn day 6 after vaccination, formation of influenza-specific B cells was lower in post-RTX group as compared with the pre-RTX group and controls (P = 0.04). Polysaccharide-specific B cells were found in 27% to 50%, being equally distributed between the groups. On day 21, the impairment of humoral responses was more pronounced with respect to influenza as compared with the pneumococcal vaccine and affected both IgG and light-chain production. Total absence of influenza-specific IgG production was observed in 55% of the post-RTX group.ConclusionsRTX compromises cellular and humoral vaccine responses in RA patients. However, repeated RTX treatment or previous anti-tumor necrosis factor (anti-TNF) treatment did not accentuate these defects.

CD25-expressing B-lymphocytes in Rheumatic Diseases

B cells play an important role in the development of autoimmune diseases due to their production of autoantibodies, antigen‐presenting capacity and production of pro‐inflammatory cytokines. The purpose of the present study was to analyse B cells from rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) patients, with respect to their expression of the IL‐2 receptor (IL‐2R) subunit CD25. Using flow cytometry, we found that CD25+ B cells from RA patients expressed significantly higher frequencies of CD122 and CD132 than CD25+ B cells from control subjects, indicating a fully functional IL‐2R. These CD25+ B cells also expressed higher frequencies of the co‐stimulatory molecule CD80, whereas IgM and IgA expression was decreased compared with CD25+ B cells from healthy controls. In addition B cells from SLE patients co‐expressed CD25 together with CD80, CD122, and CD132, but to a lower degree IgD and IgM, when compared with healthy controls. Taken together, our results indicate that CD25+ B cells from RA and SLE patients are in a highly activated state, display a more mature phenotype and suggest that this B cell subset may be involved in the pathogenesis of RA and SLE.

Cytokines in the Placenta of Pakistani Newborns With and Without Intrauterine Growth Retardation

Although intrauterine growth retardation (IUGR) is a major risk factor for increased neonatal mortality and morbidity, the mechanisms behind it are not clear. We analyzed cytokine gene expression and gene polymorphisms in infants with and without IUGR in Pakistan, where IUGR is very common. 45 IUGR and 55 control mother/infant pairs were studied. mRNA for IL-10, IL-8, TNF-α, TGF-β, IL-6, IL-4, IL-1β, IL-12, IFN-γ and GAPDH was quantified with RT-PCR from placenta. Cytokine and cytokine receptor gene polymorphisms for -1087IL10, -308TNFA, -174IL6, +915TGFB1, intron 2 IL1RN, +36TNFR1, 150V IL4RA and -159CD14 were determined from genomic DNA. The serum levels of IL-1β, IL-6, IL-8, IL-10, IL-12, TNF-α and TGF-β were measured.There was a significant decrease of IL-10 and IL-12, but increase of TGF-β in the decidua and similarly decrease of IL-10, but increase of TGF-β in the trophoblasts of the IUGR placentas compared with the non-IUGR placentas. We found significantly lower levels of IL-1β in serum from the mothers of the IUGR infants and of TGF-β in serum of the infants with IUGR compared with the non-IUGR infants. We note that the IL-10 mRNA expression in the decidua was down-regulated, but the TGF-β mRNA up-regulated in IUGR placentas of mothers from a population with multiple risk factors for IUGR. We propose that the low IL-10 in the placenta may be involved in the pathogenesis of IUGR and might possibly be treatable.

Functional Characterization of Murine CD25 Expressing B Cells

B cells are an important part of both innate and adaptive immune system. Their ability to produce antibodies, cytokines and to present antigen makes them a crucial part in defence against pathogens. In this study, we have in naïve Naval Medical Research Institute mice functionally characterized a subpopulation of splenic B cells expressing CD25, which comprise about 1% of the total B cell compartment. Murine spleen cells were sorted into two highly purified B cell populations either CD19+u2003CD25+ or CD19+u2003CD25−. We found that CD25+ B cells secreted higher levels of IL‐6, IL‐10 and INFγ in response to different TLR‐agonists, and were better at presenting alloantigen to CD4+ T cells. CD25 expressing B cells spontaneously secreted immunoglobulins of IgA, IgG and IgM subclass and had better migratory ability when compared with CD25− B cells. In conclusion, our results demonstrate that CD25+ B cells are highly activated and functionally mature. Therefore, we suggest that this population plays a major role in the immune system and may belong to the memory B‐cell population.

B-cell CD25 Expression in Murine Primary and Secondary Lymphoid Tissue

B cells are in analogy with T cells capable of expressing functional IL‐2 receptors. IL‐2R α‐chain (CD25) positive T cells have been studied in detail but not much is known about CD25 positive B cells. The aim of this study was to examine the phenotypic properties of the CD25 expressing B cells collected from different lymphoid organs in mice. Samples were stained for various cell surface markers and analysed using flow cytometry. We found that approximately 49% of B cells in bone marrow, 16% in peritoneal cavity, 2% in spleen and 1% in lymph nodes express CD25. In contrast, CD25 expressing B cells were not found in the blood or in Peyers patches. Phenotypic characterization showed that CD25+ B cells in spleen, lymph nodes and peritoneal cavity have higher expression of AA4.1, CD5, CD69, CD80, CD86, CD122, CD132, IgA, IgG and IgM on their surface in comparison with CD25− B cells. In contrast, expression of IgD and IA‐IE was lower on CD25+ B cells in spleen and lymph nodes. In bone marrow, the expression of CD5, CD80, CD86, CD122, CD132, IgA, IgD and IgM was lower, while the expression of AA4.1, IgG and IA‐IE was increased on CD25+ B cells compared with CD25− B cells. In conclusion, our results indicate that B cells expressing CD25 are phenotypically distinctly different from those that are CD25 negative. Our findings suggest that CD25+ B cells are more prone to efficient antigen presentation and display a more mature phenotype.

Phenotype and Function of CD25-Expressing B Lymphocytes Isolated from Human Umbilical Cord Blood

Background. We have shown that approximately 30% of human peripheral blood B-cells express CD25. B cells expressing CD25 display a mature phenotype belonging to the memory B-cell population and have a better proliferative and antigen-presenting capacity. The aim of the present study was to characterize the CD25-expressing subset of B cells in human cord blood. Material and Methods. Mononuclear cell fraction from human cord blood (n = 34) and peripheral adult blood (n = 22) was sorted into CD20+CD25+ and CD20+CD25− B-cell populations. Phenotype and function of these B-cell populations were compared using flow cytometry, proliferation, cytokine production, and immunoglobulin secretion. Results. CD25-expressing B cells are a limited population of cord blood mononuclear cells representing 5% of the CD20+ B cells. They are characterised by high expression of CD5 in cord blood and CD27 in adult blood. CD25-expressing B cells express a functional IL-2 receptor and high levels of CC-chemokine receptors and spontaneously produce antibodies of IgG and IgM subclass. Conclusions. CD25 expression is a common denominator of a specific immunomodulatory B-cell subset ready to proliferate upon IL-2 stimulation, possibly ready to migrate and home into the peripheral tissue for further differentiation/action.

Perinatal PUFA Intake Affects Leptin and Oral Tolerance in Neonatal Rats and Possibly Immunoreactivity in Intrauterine Growth Retardation in Man

Departments of aClinical Immunology and bPaediatrics, University of Göteborg, Göteborg, Sweden; cDepartment of Social and Preventive Paediatrics, Fatima Jinnah Medical College/Sir Ganga Ram Hospital, dDepartment of Obstetrics and Gynecology, King Edward Medical College, and eDepartment of Social and Preventive Paediatrics, King Edward Medical College, Lahore, Pakistan, and fDepartment of Rheumatology, Göteborg University, Göteborg, Sweden