Pathoma Chapter 2B Flashcards
Cytotoxic T cell killing occurs via
Secretion of perforin and granzyme; perforin creates pores that allow granzyme to enter the target cell, activating apoptosis. Expression of FasL, which binds Fas on target cells, activating apoptosis
B Lymphocytes
Immature B cells are produced in the bone marrow and undergo immunoglobulin rearrangements to become naive B cells that express surface IgM and IgD.
B-cell activation occurs via
Antigen binding by surface IgM or IgD; results in maturation to IgM or IgD secreting plasma cells, B-cell antigen presentation to CD4+ helper T cells via MHC class II
What provides the 2nd activation signal
CD40 receptor on B cell binds CD40L on helper T cell
What happens after the 2nd activation of B cells?
Helper T cell then secretes IL-4 and IL-5 (mediate B-cell isotype switching, hypermutation, and maturation to plasma cells)
What is granulomatous inflammation?
Subtype of chronic inflammation, Characterized by granuloma, which is a collection of epithelioid histiocytes
What are epithelioid histiocytes?
macrophages with abundant pink cytoplasm, usually surrounded by giant cells and a rim of lymphocytes
What is granulomatous inflammation divided into?
noncaseating and caseating subtypes
What is noncaseating granulomas?
lack central necrosis
Common etiologies for noncaseating granulomas?
include reaction to foreign material, sarcoidosis, beryllium exposure, Crohn disease, and cat scratch disease,
Caseating granulomas
exhibit central necrosis and are characteristic of tuberculosis and fungal infections
What are the steps involved in granuloma formation?
- Macrophages process and present antigen via MHC class II to CD4+ helper T cells. 2. Interaction leads macrophages to secrete IL-12, inducing CD4+ helper T cells to differentiate into THl subtype. 3. TH1 cells secrete IFN-y, which converts macrophages to epithelioid histiocytes and giant cells.
What is DiGeorge Syndrome?
Developmental failure of the third and fourth pharyngeal pouches
What is DiGeorge Syndrome?
Due to 22qll microdeletion
What does DiGeorge Syndrome presents with?
T-cell deficiency (lack of thymus); hypocalcemia (lack of parathyroids); and abnormalities of heart, great vessels, and face
Severe combined immunodeficiency
defective cell-mediated and humoral immunity
What are the etiologies for SCID?
Cytokine receptor defects, Adenosine deaminase (ADA) deficiency, MHC class II deficiency
Cytokine receptor defects
Cytokine signaling is necessary for proliferation and maturation of B and T cells.
Adenosine deaminase (ADA) deficiency
ADA is necessary to deaminate adenosine and deoxyadenosine for excretion as waste products; buildup of adenosine and deoxyadenosine is toxic to lymphocytes
MHC class II deficiency
MHC class II is necessary for CD4+ helper T cell activation and cytokine production