Ch 14: Immune System / Lymphoid Tissues & Q Bank Flashcards
BASIC IMMUNITY
2 types:
Innate immunity is present from birth and involves leukocytes (mainly granulocytes), and proteins such as defensins, complement, lysozyme, and interferons; adaptive immunity develops more slowly and is based on antigen presentation to lymphocytes.
BASIC IMMUNOLOGY
Immune cells communicate with one another by….
and regulate one another’s activities via polypeptide hormones called cytokines.
BASIC IMMUNOLOGY
What are Antigens?
They are the regions of macromolecules, usually proteins, that are recognized by lymphocytes to elicit a specific immune response against them.
BASIC IMMUNOLOGY
Antibodies are immunoglobulins produced by plasma cells after a progenitor B cell is activated by….
a specific antigen and rearranges its immunoglobulin genes so the antibody matches the antigen.
BASIC IMMUNOLOGY
Surfaces of all nucleated cells bear fragments of their constituent proteins and placed on…
on major histocompatibility complex (MHC) class I molecules.
BASIC IMMUNOLOGY
Only antigen-presenting cells (APCs), mostly derived from monocytes, also present…
fragments of endocytosed foreign (usually from microorganisms) proteins on surface MHC class II molecules.
LYMPHOCYTE ORIGINS AND DIFFERENTIATION
There are 2 kinds:
Where do they originate from?
Lymphocytes originate in the primary lymphoid organs: bone marrow for B lymphocytes and the thymus for T lymphocytes.
Lymphocyte Origins and Differentiation
While B cells produce antibodies for humoral immunity
T cells function in cell-mediated immunity.
Lymphocyte Origins and Differentiation
How do T Cells work?
T cells develop receptors (TCRs), usually containing α and β chains, that bind antigen along with another surface protein designated by a CD (“cluster of differentiation”) numbering system.
Lymphocyte Origins and Differentiation
There 4 class’s of T cells
List them:
- CD4+ T helper cells;
- CD8+ cytotoxic T cells;
- CD4+CD25+ regulatory T cells;
- and γδ T cells, which have those TCR chains and are mainly in epithelia.
Lymphocyte Origins and Differentiation
B-cell receptors (BCRs) are IgM or IgD antibodies on the cell surface that
bind specific antigens whenever they contact them.
Lymphocyte Origins and Differentiation
B and T cells are often activated, proliferate, and begin to function in the secondary lymphoid organs: Which are:
- the lymph nodes,
- all mucosa-associated lymphoid tissue (MALT),
- and the spleen.
Lymphocyte Origins and Differentiation
In these organs, lymphocytes are distributed within a meshwork of reticulin produced by
fibroblastic reticular cells,
and most APCs are dendritic cells with many processes.
Lymphocyte Origins and Differentiation
In secondary lymphoid tissues, BCRs bind antigen not
presented in MHC class II molecules of another cell, which are the follicular dendritic cell (FDC).
Lymphocyte Origins and Differentiation
With cytokines from helper T cells, a FDC-activated B cell proliferates clonally to
produce temporarily a large lymphoid nodule (or follicle), which develops a pale germinal center.