B cells in Type 1 hyper IgM syndrome patients, who cannot form GC. METHODS: To determine the origin of these CD27+ B cells, we analyzed the earliest ...
AB12 Abstracts
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The Effect Of Phototherapy On Lymphocyte Subsets In Newborn Infants R. A. A. ELFeky1, M. A. Abdel Fattah1, D. M. Gaafar1, H. M. Afifi2; 1Pediatric Department, Ain Shams University, Cairo, EGYPT, 2Clinical Pathology Department, Ain Shams University, Cairo, EGYPT. RATIONALE: Phototherapy is the mainstay treatment of neonatal hyperbilirubinemia. Previous studies found that neonatal jaundice was associated with increased parental perception of vulnerability. The study was to investigate the influence of the use of phototherapy on different lymphocyte subsets; CD3+, CD19+ and CD56+ cells after 72 hours of exposure and correlate the finding to the frequency of infections in the first six months of life. METHODS: Thirty term neonates with indirect hyperbilirubinemia were sampled before and 72 hours of exposure to phototherapy. The percentages of CD3+, CD19+ and CD56+ cells were assessed by flow cytometry. The study group were followed-up for a period of 6 months with monitoring of the growth pattern, frequency of infections and the need for hospitalizations. RESULTS: The percentage of CD3+ and CD19+ lymphocyte subsets were significantly lower at 72h of exposure to phototherapy. CD56+ cells were decreased as well at 72h of exposure to phototherapy yet the decline was statistically insignificant. Patients with a higher decline in CD3+ cells had an increase in the number of hospital visits (r50.64, p50.05). CONCLUSION: Phototherapy affects the immune system by affecting the lymphocyte subsets percentages even after a short duration of exposure. The effect on T cells number might contribute to the vulnerable child syndrome. CD27+ Developing B Cells are Common in Human Fetal Liver L. M. McWilliams, K. Y. Su, X. Liang, S. Floyd, J. Amos, M. Moody, G. Kelsoe, M. Kuraoka; Duke University Medical Center, Durham, NC. RATIONALE: CD27 is generally accepted as a marker of post-germinal center (GC) memory B cells. However, several observations challenge this consensus, including expression of CD27 on na€ıve, IgM+ fetal-origin B cells in umbilical cord blood and the presence of CD27+ peripheral blood B cells in Type 1 hyper IgM syndrome patients, who cannot form GC. METHODS: To determine the origin of these CD27+ B cells, we analyzed the earliest source of human B cell ontogeny, fetal liver. _85%) of CD19+ B RESULTS: In 13 and 19 week human fetal liver, most (> cells express CD10, a marker for developmental immaturity. Surprisingly, 6-8% of these CD19+CD10+ B cells express CD27; further analysis revealed that CD27 expression could be detected at the earliest stage of Bcell commitment, CD19+CD10+IgM-IgD-CD34+ pro-B cells. This CD27 expression subsequently continued in the B-lineage at least until the appearance of IgM+ immature/transitional B cells. Similar CD27+CD19+ cells with a pro-B, pre-B, and immature/transitional B-cell phenotype are present, albeit less frequently (1.6 %-0.5 %), in adult bone marrow. Consistent with patterns of gene expression in conventional (CD27-) proB, pre-B and immature/transitional B cells, high levels of recombination activating gene-1 (RAG-1), terminal deoxynucleotidyl transferase (TdT), and Vpre-B mRNA are present in CD27- pro/pre-B cells from fetal liver and adult bone marrow, but undetectable in (CD27+CD19+CD10+IgM+) immature/transitional B cells. When CD27+ pro-B cells are cultured, these cells efficiently differentiate into pre-B and IgM+ immature/transitional B cells. CONCLUSIONS: Our findings suggest a distinct, fetal origin for a subset of CD27+IgM+ B cells that is minimized in adults.
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J ALLERGY CLIN IMMUNOL FEBRUARY 2012
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Intravenous Immunoglobulins Suppress Antibody-Dependent Effector Functions of Human Peripheral Blood Cells S. Bunk, A. Trbic, A. M. Winkler, A. Weber, H. P. Schwarz, B. M. Reipert, C. Hermann; Baxter BioScience, Vienna, AUSTRIA. RATIONALE: Several studies have shown the importance of self-reactive antibodies in the maintenance of autoimmune diseases. Therefore, we asked whether IGIV, which is therapeutically effective in some of those diseases, directly modulates antibody-mediated effector functions. METHODS: We used a human in vitro system to analyze potential modulatory effects of IGIVon effector functions in antibody-dependent cellular cytotoxicity (ADCC). Human peripheral blood mononuclear cells (PBMC) from 47 healthy volunteers were pre-incubated with IGIV and then added to human breast cancer cells (SK-BR3) opsonized with a specific antibody. The cytotoxic damage to SK-BR3 cells was determined by measuring lactate dehydrogenase release into supernatants. IGIV-mediated effects on viability and Fc gamma receptor (FcgR) expression of PBMC were analyzed by flow cytometry. RESULTS: Pre-incubation of PBMC with IGIV for 48h resulted in a marked inhibition of ADCC, ranging from 15% to 74% (mean 42%) which could not be mimicked with human monoclonal IgG1 and IgG2 antibodies. Flow cytometric analysis indicated that IGIV induced natural killer (NK) cell death, which significantly correlated with ADCC inhibition. The IGIVinduced decrease in NK cell viability was not triggered by FcgR ligation since the addition of FcgR blocking antibodies could not prevent cell death induction. Furthermore, IGIV enriched for sialic acid bearing glycans by lectin affinity chromatography with Sambucus nigra agglutinin showed no differences in the effects on NK cell viability and ADCC compared with non-enriched IGIV. CONCLUSIONS: IGIV modulates antibody-dependent effector functions of human immune cells, which could contribute to the modulatory activities of IGIV in inflammatory and autoimmune diseases.
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Physiologic DNA Breaks Activate Non-canonical NFkB Signaling in Developing B Cells A. A. Trott, J. J. Bednarski, B. P. Sleckman; Washington University School of Medicine, St. Louis, MO. RATIONALE: Previous data demonstrated that DNA breaks generated during antigen receptor recombination activated an NFkB-dependent gene cohort. One of these genes was p100, the key regulator of the alternative NFkB pathway. Non-canonical NFkB participates in early B cell development but its mechanism of activation remains unknown. We hypothesized that DNA breaks activate alternative NFkB to regulate specific genes. METHODS: Gene expression was assessed by QRT in pre-B cell lines deficient in p100. Cells were reconstituted with p100 to confirm gene targets, and mutations of p100 were introduced to assess its regulation by DNA breaks. RESULTS: Activation of the non-canonical NFKB pathway in early B cells was dependent on induction of DNA breaks. p100 regulates the expression of a defined gene cohort in a manner dependent on DNA damage responses. CONCLUSIONS: Non-canonical NFkB is activated in early B cells by DNA breaks. DNA break signals can integrate with surface receptor signals to tune NFkB signaling and direct lymphocyte development.
