Monocyte and lymphocyte membrane markers: Ontogeny and clinical significance
Gabriel Virella in Medical Immunology, 2019
There are three major types of lymphocytes: T cells, B cells, and NK cells. T cells and B cells comprise the cellular arm of the adaptive immune system. The immune system is controlled by balance of stimulatory and inhibitory signals mediated by lymphocyte membrane markers. Engagement of activation receptors on lymphocytes can induce cellular migration, proliferation, differentiation, anergy, or apoptosis. Several factors that influence the outcome include antigen concentration, binding avidity, duration of antigen recognition, association with co-stimulatory molecules, cytokines, and the developmental stage of the lymphocyte. Engagement of cellular inhibitory receptors will inhibit functional responses. In most cases, conserved sequences within the cytoplasmic domains of the receptors and/or association with intracellular adapter proteins mediate the activation or inhibitory cascade. Most inhibitory receptors contain one or more copies of the conserved tyrosine-based inhibitory motif (ITIM) within the cytoplasmic domain. Upon receptor ligation, inhibitory signaling is mediated by tyrosine phosphorylation within this region and the subsequent recruitment of the tyrosine-specific phosphatases, SHP-1 and SHP-2 or the phospholipid-specific phosphatases, SHIP. In general, these phosphatases work by degrading phosphatidylinositol triphosphate or decreasing the phosphorylation of intracellular signaling proteins such as ZAP70, Syk, and phospholipase Cγ. In a similar fashion, activation receptors share common signaling pathways mediated by the transmembrane association with adapter proteins containing the conserved tyrosine-based activation motif (ITAM).
Free Radicals Damage Cells
Robert Fried, Lynn Nezin in Evidence-Based Proactive Nutrition to Slow Cellular Aging, 2017
A study published in the European Respiratory Journal, in 2006, reported the effects of tobacco smoking on telomere shortening in circulating lymphocytes. Lymphocytes are a type of white blood cell, part of the immune system protecting us from bacteria, viruses, fungi, and parasites. The aim of the study was to determine whether telomere abbreviation was further amplified in smokers who develop chronic obstructive pulmonary disease (COPD). Telomere length was determined in circulating lymphocytes from never-smokers, smokers with normal lung function, and smokers with moderate-to-severe airflow obstruction. In contrast to never-smokers, telomere length decreased significantly with age in smokers. There was also a dose–effect relationship between the cumulative long-life exposure to tobacco smoking (pack/years) and telomere length. The presence and/or severity of chronic airflow obstruction did not modify this relationship. The authors concluded that smoking exposure enhances telomere shortening in circulating lymphocytes with a direct dose–effect relationship between exposure to tobacco smoking and telomere length—the longer the duration of smoking, the shorter the telomeres. This effect was not increased in smokers who develop COPD (Morlá et al. 2006). Other studies also supported the finding of shorter telomeres in different cell types proportional to the duration of smoking (Babizhayev et al. 2011 ).
Cellular Components of Blood
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
Lymphocytes are immunologically competent cells that assist and add specificity to the defence of the body against infection. About 20%–40% of all white cells are lymphocytes. These come in two types from common stem cells in fetal bone and complete their development either via the bone itself (B lymphocytes) or in the thymus (T lymphocytes). The bone marrow is the primary lymphopoietic organ where lymphocytic stem cells are produced in response to non-specific cytokines in post-natal life. In the fetus, the yolk sac, liver and spleen are the primary sites. The secondary lymphopoietic sites are the lymphoid tissue found in the lymph nodes, spleen and respiratory tract.
Association between T lymphocyte sub-sets apoptosis and peripheral blood mononuclear cells oxidative stress in systemic lupus erythematosus
Published in Free Radical Research, 2011
Dilip Shah, Ashish Aggarwal, Archana Bhatnagar, Ravi Kiran, Ajay Wanchu
Increased oxidative stress and lymphocyte apoptosis are a hallmark of the autoimmune disease systemic lupus erythematosus (SLE). However, the association between oxidative stress and T lymphocytes apoptosis has still to be elucidated in SLE. In order to appraise the interaction between oxidative stress and T lymphocyte apoptosis with the severity of disease, oxidative stress profile and T lymphocytes apoptosis were studied. Increased levels of ROS, MDA and CD4+ lymphocyte apoptosis were positively associated with disease activity while decreased levels of GSH and percentage expression of CD4+ lymphocyte were negatively associated with disease activity. The decrease in intracellular levels of GSH was negatively associated with T lymphocyte, CD4+ lymphocyte, CD8+ lymphocyte apoptosis and intracellular caspase-3 expression. The present study suggests that increased T lymphocyte sub-sets apoptosis may be mediated by decreased intracellular glutathione concentration and severity of disease might be enhanced together by over-production of ROS in SLE.
Effect of High-Dose Methylprednisolone and G-CSF Treatments on Lymphocyte Subtypes in Neutropenic Children with Acute Lymphoblastic Leukemia: A Pilot Study
Published in Pediatric Hematology and Oncology, 1998
Namik Özbek, Sevgi Yetgin, A. Murat Tuncer
Treatment of neutropenia with corticosteroids and hemopoietic growth factors may cause alterations in the immune system. This study investigated and compared the effects of various regimens (HDMP, G-CSF, and G-CSF + HDMP) on total lymphocyte counts and subtypes in neutropenic patients with acute lymphoblastic leukemia. Lymphocyte subtypes were studied just prior to treatment and 1 week later. In the HDMP group, total lymphocyte counts and the numbers ofCD3+, CD4+, CD8+, and CD 19+ lymphocytes and monocytes increased, while the helper/supressor lymphocyte ratio decreased. No significant changes were seen in lymphocyte subtypes in the G-CSF and G-CSF+ HDMP groups, apart from an increase in total lymphocyte numbers. In the control group there was an increase in the number of CD3+ and CD8+ lymphocytes and a decrease in the helper/supressor lymphocyte ratio. These results suggest that HDMP has an inducing, rather than a suppressive effect on all lymphocyte subtypes studied.
The Effect of Delta-9-Tetrahydrocannabinol and 11-Hydroxy-Delta-9-Tetrahydrocannabinol on T-Lymphocyte and B-Lymphocyte Mitogen Responses
Published in Journal of Immunopharmacology, 1985
T. W. Klein, C. A. Newton, R. Widen, H. Friedman
Previous studies have shown that delta-9-tetrahydrocanna-binol (THC) suppresses T-lymphocyte proliferation when added to human cell cultures. We report that THC when added to mouse splenocyte cultures suppressed T-lymphocyte (Con A, PHA) and B-lymphocyte (LPS) mitogen-induced proliferation. Although the ED50 concentrations (5ug/ml; 1.6×10−5 M) of THC were similar for suppressing all three mitogen responses, higher threshold concentrations of drug were required to effect suppression of the T-lymphocyte mitogen responses. Complete suppression of T- and B-lymphocyte responses was achieved with THC concentrations (8ug/ml or 2.6×10−5 M) which were not directly toxic as judged by vital dye exclusion. The hydroxylated metabolite of THC, 11-hydroxy-THC, was observed to be much less potent in the inhibition of lymphocyte proliferation. However, as with the parent compound, B-lymphocyte responses appeared to be the most affected by the drug. Additional studies demonstrated that both T- and B-lymphocyte proliferation is rapidly suppressed following THC treatment, not affected by a 24 hr. pretreatment with THC, and not as readily suppressed by THC in cultures containing 20% serum. Thus, THC appears to inhibit both T- and B-lymphocyte proliferation with B-lymphocyte responses displaying greater inhibition at lower drug concentration. The 11-hydroxy metabolite is much less suppressive in this system than the parent compound.
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