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Immune Reconstitution after Hematopoietic Stem Cell Transplantation
Published in Richard K. Burt, Alberto M. Marmont, Stem Cell Therapy for Autoimmune Disease, 2019
Andreas Thiel, Tobias Alexander, Christian A. Schmidt, Falk Hiepe, Renate Arnold, Andreas Radbruch, Larissa Verda, Richard K. Burt
SHM, gene conversion, and CSR take place in germinal center B cells in response to BCR antigen stimulation. This results in high affinity antibodies with specialized effector functions. The reactions are dependent on T cell and germinal center follicular (epithelial) cell help.71 T cells communicate with B cells via a number of membrane bound receptor ligand complexes such as B cell CD40 and T cell CD40 ligand (CD40L). Interaction of CD40 with CD40L promotes B cell proliferation and CSR.76 If the CD40-CD40L interaction is blocked, B cells cannot proliferate and produce immunoglobulin.77 Interestingly, most lymphomas are B cells arising in the lymph node germinal center and involve oncogene translocations possibly due to errors in targeting of the SHM and CSR enzymes.78
Immune System Imaging
Published in Margarida M. Barroso, Xavier Intes, In Vivo, 2020
Michael J. Hickey, M. Ursula Norman
One of the major responses that takes place in the lymph node is development of antibody-mediated humoral immunity via antigen-dependent activation and maturation of B cells. Studies with intravenously delivered antigens have revealed that following uptake of target antigen, B cells migrate preferentially toward the border between T and B cell zones (Okada et al., 2005). In this location, they are able to undergo interactions with CD4+ T cells, forming mobile B cell-T cell conjugates. These cells then migrate back into the follicle and initiate the germinal center reaction, the ultimate outcome of which is plasma cell development and generation of high affinity antibodies (Okada et al., 2005).
A review on biological occurrence, bioaccumulation, transmission and metabolism of chlorinated paraffins
Published in Critical Reviews in Environmental Science and Technology, 2023
Weifang Chen, Jiyan Liu, Xingwang Hou, Guibin Jiang
CPs have adverse effects on organisms and can induce developmental toxicity (Liu et al., 2016; Ren et al., 2018), neurotoxicity (Yang et al., 2019), endocrine disruption (disruption of thyroid hormone homeostasis) (Gong et al., 2018), and endogenous metabolism disruption (Geng et al., 2015; Peng et al., 2020; Ren et al., 2019). The 13-day 50% lethal concentration (LC50) of SCCPs with 56.5% Cl in zebrafish embryos was found to be 34.3 μg/L while long-term exposure to SCCPs enhances the risk of toxicity to aquatic biota (Ren et al., 2018). Using the immobilization test, the 48-h half maximal effective concentration (EC50) of CPs with varying chlorine content (44–62%) was found to be 42.0–152.8 μg/L in Daphnia (Koh & Thiemann, 2001). Studies showed that C9-13-CPs (mCl = 52%, C9:C10:C11:C12:C13 = 1:1:1:1:1) exposure has immunomodulatory effects (enlarged spleen and germinal center delimitation) in male mice at doses of 10 and 100 mg/kg/day (Wang, Zhu, Kong, et al., 2019). Studies on the neurotoxicity of commercial CPs with different chlorine contents (CP-42, two CP-52, and CP-70; 0–1000 μg/L) in zebrafish larvae at 5 days post-fertilization showed that CPs with a high chlorine content strongly influence the neurobehavioral parameters (Yang et al., 2019). Furthermore, exposure to environmental levels of SCCPs, MCCPs, and LCCPs leads to metabolic abnormalities in zebrafish embryos and hepG2 cells (Geng et al., 2015; Ren et al., 2018, 2019; Zhang et al., 2018). Interestingly, the effect of SCCPs on zebrafish metabolism is positively associated with the carbon chain length (Peng et al., 2020). The toxicity of CPs is influenced more by the degree of chlorination than the length of the carbon chain. This might be due to the high electron-withdrawing effects of chlorine which increases the electrophilicity of C atoms (Castro et al., 2018; Gong et al., 2018; Liu et al., 2016; Peng et al., 2020; Wang, Zhu, Kong, et al., 2019; Yang et al., 2019). These studies suggest that CPs are potentially toxic, and CP congeners with more chlorine atoms have more adverse effects. Considering their high toxicity, further studies and systematic reviews on the biological behaviors (bioaccumulation, transmission, biotransformation, etc.) of CPs are needed.