Cells of the Adaptive Immune System PDF

WELCOME! BMS 545 IMMUNOLOGY SEPTEMBER 18, 2024  ANNOUNCEMENTS  Brief exam discussion Friday, secure exam review today!  Office Hours  Tuesday 4-5 pm (virtual)  Thursday 4-5 pm (316J)  DITKI- RE-WATCH Blood Cell Lines by 12:59pm Friday  CBL’s will be graded by 9/23/24 by 5 pm at...

WELCOME! BMS 545 IMMUNOLOGY SEPTEMBER 18, 2024  ANNOUNCEMENTS  Brief exam discussion Friday, secure exam review today!  Office Hours  Tuesday 4-5 pm (virtual)  Thursday 4-5 pm (316J)  DITKI- RE-WATCH Blood Cell Lines by 12:59pm Friday  CBL’s will be graded by 9/23/24 by 5 pm at the latest  (It’s written on the CBL instruction page- I always post when to expect grades for larger assignments ) POP QUIZ  https://www.stemcell.com/virtual-conference-exhibition/immunology/immune-cell-quiz  OR  https://www.biolegend.com/en-us/immune-cell-quiz  OBJECTIVES  Compare & contrast how adaptive immune system differs from innate immune system  List unique features of the adaptive immune system (specifically immune cells)  Describe the function & role of each common lymphoid progenitor descended cell (& various subtypes) & be able to identify them based on generalized picture, description of function, or histology (if applicable)  List known inducing cytokine and key effector cytokines  State where you would expect to find receptors of the adaptive immune system within the context of the cell and correlate the ligands and receptors of the two main lymphocytes with their signaling outcomes; e.g. TCR, BCR (we’ll also talk more about this later!)  Compare and contrast the subtypes of T cells (αβ T cells, CD4+ (& 5 subtypes), CD8+ (Tc & Ts), γδ T cells)  HEMATOPOIESIS All cells in blood are derived from pluripotent stem cells (aka hematopoietic stem cells (HSCs)) in bone marrow HSCs capable of self-renewal May differentiate into any of the cellular components of blood Exact developmental pathways of some cell types (NK cells, dendritic cells, mast cells) are not yet known Differentiation into specific cell types is influenced by the array of cytokines & growth factors present Common Myeloid Progenitor Common Lymphoid Progenitor  CYTOKINES & GROWTH FACTORS INVOLVED IN DIFFERENTIATION  Erythropoietin (EPO)  Granulocyte Colony Stimulating Factor (G- CSF)  Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF)  Macrophage Colony Stimulating Factor (M- CSF)  Interleukin-3 (IL-3)  Interleukin-5 (IL-5)  Interleukin-7 (IL-7) LYMPHOID CELLS “relating to lymphatic system”  Lymphocytes produced in bone marrow travel through lymphatic system & further differentiate/ proliferate within lymphoid tissue (lymph nodes, thymus, spleen) Yes, know subtypes of Common T-cell precursor & Common ILC precursor +ILC & LTi COMMON ILC PRECURSOR: NK CELLS, ILCS, LTI FIGURE 1.18 EFFECTOR LYMPHOCYTES OF INNATE AND ADAPTIVE IMMUNITY  NATURAL KILLER CELLS (HAVE NEITHER BCR OR TCR)  Approximately 5%-10% of peripheral blood lymphocytes  Develop within bone marrow & lack CD3 (so CD3-) & TCR produced by rearrangement of TCR genes, also lack B-cell receptor  Granular appearance from cytoplasmic granules containing perforin & granzyme that can damage membranes of cells they attack  NK cells do not express antigen-specific receptors & do not undergo clonal selection  Have receptors that recognize certain microbial molecules, antibody, & class I MHC molecules  Receptors known as Killer Activation Receptor (KAR) & Killer Inhibition Receptor (KIR) allow them to recognize host cells that might need to be destroyed  NK cells play an important role in the early stages of viral infection (before adequate CD8+ Cytotoxic T cells have had time to be selected and expanded)  NK & NKT CELLS True NK cell on left, NKT on  Kill certain virally infected cells & tumor cells without prior right sensitization such as:  some virus-infected cells  cells covered with antibody  cells that do not express normal levels of class I MHC  Play a role in both innate AND adaptive even though they are descended from CLP  Similar to Innate Lymphoid Cells (ILCs) & Lymphoid tissue inducer (LTi)  Lymphoid cells that function in innate immune system  (*NEW*) Natural Killer T cell (NKT)- a unique subset of T cells develop within thymus & express a rearranged TCR of extremely limited repertoire  Unlike T cells, NKT respond to lipids, glycolipids, or hydrophobic peptides presented by a specialized, nonclassical MHC class I molecule (CD1d), & secrete large amounts of cytokines, especially IL-4  INNATE LYMPHOID CELLS  Innate Lymphoid Cells (ILCs): lymphoid cells found in all tissues, especially mucosal surfaces, that are activated by cytokine signals & participate in innate immune function  Activated early in the immune response to infection and injury, producing cytokines that direct the immune response  Assist with tissue homeostasis  Assist with tissue repair  Unlike classic lymphocytes (B & T cells), ILCs do not need antigen to become activated  https://www.youtube.com/watch?v=CXz6FVqPqHw  Lymphoid tissue inducer (LTi)- a type of innate lymphoid cell (ILC) that are essential for the development of lymph node and Peyer’s patches The Lymphocyte Army  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 thymus, but develop within 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 neonatal period, are continuously replaced from bone marrow, & are widely distributed throughout lymphoid organs & tissues  Each B cell is specific- it produces immunoglobulin of only one antibody specificity that recognizes only one epitope.  Extreme diversity among B cells, each producing a single form of immunoglobulin, that generates overall diversity of the antibody response  PLASMA CELL  Derive from terminally differentiated B cells & are immunoglobulin producing AND secreting cells  Increased size & metabolic activity than B cells & are factories that produce large quantities of immunoglobulin during their short life span