Immunology Chapters 7-10 (Exam 2) Flashcards
B cells begin their lives in the BM. The initial __________________ differentiation step in BM ultimately leads to the mature naive B cells. Mature B cells migrate to secondary lymphatic organs/tissues such as spleen and lymph nodes and begin __________________ stages of B cell differentiation to plasma cells or memory B cells
antigen-independent, antigen-dependent
After B cells are activated by an antigen and helper T cells, the antibody is secreted by plasma cells. The Ab has 3 main functions in humoral immunity. What are they?
1) neutralization
2) opsonization
3) complement activation
Which Ab is always secreted first?
IgM
What is the major function of plasma cells?
secrete Abs
Which Abs can do neutralization? How do they do neutralization?
IgM, IgG, and IgA can neutralize the epitope by surrounding it and preventing the bacteria from multiplying
Which Ab is an opsonin? How does this work?
IgG coats the epitope to make it yummy for macrophages to eat it
Which complement protein is used in opsonization?
C3b
Which Abs help with complement activation?
IgM and IgG
During the process of _____________, antigens are bound by Ab and/or complement molecules. Phagocytic cells express receptors that bind opsonin molecules; With the antigen coated with these opsonin molecules, binding of the antigen to the phagocyte is greatly enhanced.
opsonization
Some B-cells, do not differentiate into plasma cells, but remain as long-lived “___________”. Upon subsequent encounter with the same Ag, these memory cells undergo the immune memory phenomenon.
memory cells
_____________, also known as anamnestic response, is the rapid response with more Ab production with a booster shot or in a natural reencounter of antigen. Lymphocytes remember the past stimulation. After they encounter the same Ag again, B lymphocytes immediately go into action without much delay.
Immune memory
T/F: a vaccine is an antigen
true
What is class switching?
first Ab is always IgM
but then can switch to IgG, IgA, or IgE as needed
What is the difference between primary and secondary immune response with an antigen?
Cell Mediated Immunity is especially important for destroying intracellular bacteria, viral infections
and tumor cells. The effector cells involved in the Cell Mediated Immunity are….
-cytotoxic T lymphocytes (CTLs)
-NK-cells
-K-cells (killer cell, type of NK cell)
Do NK cells have MHC 1 or 2?
NEITHER
Cytotoxic T lymphocytes (CTLs), like other T-cells are both antigen and MHC-restricted. CTLs require recognition of a specific endogenous antigenic determinant; and recognition of “self” MHC. CTLs recognize antigen via their T-cell receptor. This receptor makes specific contacts with the antigenic determinant and the target cell’s class ____ MHC molecule. CTLs also express CD____, which may assist the antigen recognition process.
1, 8
A host cell infected with a virus or cancer cell display the antigens on its surface complexed with a Class I MHC molecule. When recognition takes place, the CD8 co-receptor on the CD8 T cell binds to the MHC I on the Nucleated Cell. When activated CTLs recognize antigen fragments, the T cells begin to secrete toxins (______________________________) that cause lysis or apoptosis of the infected cell
perforin and granzymes
NK cells are part of a group know as the “large granular lymphocytes”. These cells are generally non-specific (Innate Immunity), MHC unrestricted cells involved primarily in the elimination of….
neoplastic or tumor cells
NK-cells contain immunoglobulin Fc receptors on their surface and are involved in ______________________ (ADCC). ADCC occurs as a consequence of antibody being bound to a target cell surface via specific antigenic determinants expressed by the target cell. Once bound, the Fc portion of the immunoglobulin can be recognized by the K-cell. Killing then ensues by a mechanism similar to that employed by CTLs.
Antibody-dependent Cell-mediated Cytotoxicity
(this is not humoral immunity, this is still cell mediated because of use of perforin and granzyme)
Antibody-dependent Cell-mediated Cytotoxicity (ADCC) can result in type ____ hypersensitivities, for example, rheumatic fever from S. pyogenes
2
The complement system found in the blood of mammals is composed of 26 heat labile substances (proteins) that combine with antibodies on cell surfaces. Most of the complement components are numbered (e.g. C1, C2, C3, etc.) but some are simply referred to as “Factors”. The complement system must be activated in order to function, which can be activated via three distinct pathways. All of which lead to the production of C3 (the end of the early stage). What are the 3 pathways?
1) classical pathway
2) lectin pathway
3) alternative pathway
Are complement proteins always active?
no they circulate in the blood inactively until they’re needed
What cells produce complement proteins?
liver cells
