Intro to the Immune System Flashcards
What cells are found in the cortex of a lymph node?
B Lymphocytes
What do B cells in the cortex do after encountering antigen?
They form a germinal center and undergo proliferation
What cells are found in the paracortex of a lymph node?
T Lymphocytes
What cells are found in the medulla of a lymph node?
APC’s (essentially macrophages)
What are the cells of the myeloid lineage?
Eosinophils, Basophils, Neutrophils (PMN’s), Monocytes, Macrophages, Dendritic cells
What is the main function of eosinophils?
Protection against parasites
What is the main function of basophils?
Protection against parasites (similar to eosiniphils)
What is the main function of Neutrophils?
Short lived, primary phagocytic cell of the innate immune system
What is the function of monocytes?
Circulating precursors of tissue macrophages
What is the function of macrophages?
Mononuclear phagocytic cells in the tissue, derived from monocytes, participate in innate and adaptive immunity
What is the function of dendritic cells?
Antigen presentation to lymphocytes
Antigen presenting cells
What are the cells of the Lymphoid Lineage?
Large lymphocytes: NK cells
Small lymphocytes: B and T cells
What is the function of NK cells?
Innate immunity to viruses and tumors
What is the function of B cells?
Ab production
What is the function of T cells?
Cytokine production
Granulocyte CD?
CD15+
Monocyte CD?
CD14+
Dendritic CD?
CD11c+
T Lymphocyte CD?
All T lymphocytes are CD3+
T helper lymphocyte CD?
CD3+ CD4+
Cytotoxic T lympocyte CD?
CD3+ CD8+
B lymphocyte CD?
CD19+
NK cell CD?
CD56+
What are the proportions of immune cells in the blood?
Neutrophils (40-75%) > Lymphocytes (20-50%) > Monocytes (2-10%) > Eosinophils (1-6%) > Basophils (NL-MEB)
Where are blood borne pathogens filtered and create an immune response?
The spleen
The lymph node collects antigen from where?
Epithelium and connective tissue
What are self antigen (markers of self?)
MHC molecules, which in humans are made up of various HLA types
What are the HLA types of Class I MHC, and where are they found?
MHC type I:
HLA type A, B, C
Found in virtually all tissues
What are the HLA types of Class II MHC, and where are they found?
MHC type II:
HLA type DP, DQ, DR
Found exclusively in B cells, monocytes/macrophages, and Dendritic cells (These are antigen presenting cells, they carry MHC class II in addition to MHC class I)
What are components of the innate immune system?
Barriers (skin, tears), Macrophages, Granulocytes, NK cells
What are components of the adaptive immune system?
T cells (cell-mediated) and B cells (humoral)
What is cell mediated immunity, and against what is it directed?
killing of cells by cytotoxic T lymphocytes (CTL’s) and the production of cytokines
directed against infected cells, defective cells, and non-self cells
What is humoral immunity and against what is it directed?
antibodies produced by immunoglobulin-producing B cells (plasma cells)
directed against cell associated and free floating antigen
What do T helper cells secrete when they are activated by antigen, and what does it do?
cytokines –> are absolutely necessary for other T and B cells to terminally differentiate
What happens to a cytotoxic T cell when it is activated by antigen?
It produces perforin & granzymes that it will release directly into the target cell via cell-cell contact
Do B cells require antigen presentation in the context of self?
No – B cell Ig binds to the antigen itself, without the need for self antigen
What is necessary for a T helper cell to bind Ag?
A T helper cell (CD4+) requires Ag presented in the context of MHC class II
What is necessary for a cytotoxic T cell to bind Ag?
A cytotoxic T cell (CD8+) requires Ag presented in the context of MHC class I
Describe the process after a B cell recognizes a foreign Ag
A B cell Ig recognizes Ag presented by an antigen presenting cell
The Ig/Ag is endocytosed and is broken down along with the Ag attached to it
The B cell places Ag peptide in the context of MHC Class II and displays it on the surface
The B cell Ag/MHC-II stimulates a helper T cell, which proliferates, terminally differentiates, and produces cytokines
The cytokines stimulate B cells to terminally differentiate into plasma cells which secrete Ig against the specific Ag
The cytokines also stimulate cytotoxic T cells to proliferate and differentiate and migrate to kill infected cells
Give some examples of passive immunity. Is it short or long term?
Mother passing Ab to her infant, antiserum
Short term
Give some examples of active immunity. Is it short or long term?
Naturally acquired (infection), vaccination
Long term
What are the two types of autoimmune diseases?
Give some examples of each
Organ specific: MS, type I diabetes, Hashimoto’s Thyroiditis
Systemic: Systemic Lupus (SLE), Rheumatoid Arthritis
