Intro to B Cells & Development PDF
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Uploaded by .keeks.
Marian University
2024
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Summary
This document provides an introduction to B cells and their development. It explains the differences between innate and adaptive immunity, the roles of B cells and plasma cells, and where B cells develop in the body. It's focused on an understanding of B cell development.
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WELCOME! BMS 545 IMMUNOLOGY OCTOBER 16, 2024 ANNOUNCEMENTS No more true “homework” until Module 4 I will post an exam debrief video once all students have taken the exam so I can talk more freely I will post CBL answers once I am done grading! Office hours back to normal! Tuesday 4...
WELCOME! BMS 545 IMMUNOLOGY OCTOBER 16, 2024 ANNOUNCEMENTS No more true “homework” until Module 4 I will post an exam debrief video once all students have taken the exam so I can talk more freely I will post CBL answers once I am done grading! Office hours back to normal! Tuesday 4-5 pm virtual Thursday 4-5 pm in-person (316J) DID EVERYONE HAVE A GOOD FALL BREAK? ANYTHING EXCITING? ADAPTIVE IMMUNITY & B-CELL REVIEW OBJECTIVES Describe how adaptive immune system differs from innate & unique features of the adaptive immune system Describe the function & role of each adaptive immune cell* & be able to identify them based on generalized picture, description of function or histology Describe how B cell graduates can be differentiated & where they can be found during gestation Recognize & describe the microenvironments where adaptive immune cells* mature & the adaptive immune response develops Identify the primary & secondary immune organs in vertebrates & describe their function in relation to the adaptive immune system & adaptive immune cells* Describe the environment where B cells develop Describe how bone marrow stromal cells play a role in driving B cell development *With a focus on B cells & plasma cells! INNATE VS. ADAPTIVE IMMUNITY PURPOSE OF ADAPTIVE IMMUNE SYSTEM Steps in when innate immune system fails Comprises immunological memory- ability to recognize & remember specific pathogens via their antigens Produces antibodies Humoral immune response- “fluids” that prevent or defend against microbial attack Antibodies recognize and bind to microbial epitopes: to prevent microbial spread by immobilization (agglutination) prevention of microbial attachment to host cells (neutralization) promotion of microbial phagocytosis and clearance (opsonization) targeting of microbial destruction by soluble molecules (complement) or by leukocytes Cell-mediated immunity- leukocytes destroy invading cells The Lymphocytes LYMPHOCYTES “Relating to lymphatic system” Lymphocytes produced in bone marrow travel through lymphatic system and further differentiate/ proliferate within lymphoid tissue (lymph nodes, thymus, spleen) INTRO TO B-CELL DEVELOPMENT Hematopoietic stem cells in bone marrow become common lymphoid precursor (CLP) lineage Differentiates in thymus (T- cells) Remains in bone marrow (B-cells) B-cell “graduates” in each of these groups can be differentiated by: extent of their “education” arrival & departure from B.M. diversity or “repertoire” of BCRs geographic distribution in body nature of responses to LYMPHOCYTES Lymphocytes are defined by where they undergo “basic training” & by the type of receptors they display on their cell surfaces: TCR (T cells & NKT cells), BCR or immunoglobulins (B cells), or neither (NK cells) Bone marrow-derived cells: Not all lymphocytes of bone marrow origin are destined for thymic education Certain lymphoid cells remain & develop in the bone marrow & are precursors of immunoglobulin-producing lymphocytes B cells- synthesize immunoglobulin and display it on their surfaces, where it functions as their BCR Plasma cells- derived from differentiated, mature B cells and both synthesize and secrete immunoglobulin B-CELL Do not migrate to the thymus but develop within the bone marrow Arise from HSCs in the bone marrow Two distinct lineages: B-1 & B-2 cells B-1 cells (first to develop embryologically)- self-renewing population that dominates the plural & peritoneal cavities B-2 cells (conventional) arise during & after the neonatal period, are continuously replaced from the bone marrow, & are widely distributed throughout the lymphoid organs & tissues Each B cell is specific- it produces immunoglobulin of only one antibody specificity that recognizes only one epitope. It is the extreme diversity among B cells, each producing a single form of immunoglobulin, that generates the overall diversity of the immunoglobulin (or antibody) response Chapter Opener B-CELLS!! B-CELL LINEAGE OVERVIEW In humans, progenitors of immunoglobulin-producing cells are found during gestation: 3rd week- yolk sac 8th week- fetal liver ~12th week- bone marrow Called “bone marrow–derived lymphocytes” or B cells because this is where most of these cells differentiate B cells are cells that synthesize immunoglobulin & display it on their surfaces as their BCRs Once they become activated, they differentiate into plasma cells which can then synthesize AND secrete their BCR as an antibody PLASMA CELL Derive from terminally differentiated B cells & are immunoglobulin-producing AND immunoglobulin- secreting cells Characterized by basophilic cytoplasm, a nucleus that has a stellate (starlike) pattern within it, and non-staining Golgi Cease to use immunoglobulin as a membrane receptor & instead secrete it into the fluids around them Secreted immunoglobulin known as “antibodies” With increased size & metabolic activity, are factories that produce large quantities of immunoglobulin during their short life span of