39 Questions
What is the specialized integral membrane protein complex on cell surfaces that bind antigens recognized by lymphocytes?
Major Histocompatibility Complex (MHC)
Which type of protein plays a crucial role in the immune rejection of grafted tissue or organs?
MHC class I
What are the human cell counterparts of MHC class I and class II proteins often called?
Human Leukocyte Antigens (HLAs)
What do T lymphocytes recognize on MHC proteins?
Epitopes
Where are MHC molecules synthesized before they leave the cell?
Rough Endoplasmic Reticulum (ER)
What happens if the MHCs on cells of a tissue graft are not similar to those encountered by T lymphocytes during development?
Strong immune reaction is induced
What do T lymphocytes consider unfamiliar MHC epitopes on graft cells as?
"Non-self" markers
Which organelles are involved in the production of MHC class I proteins?
Golgi Apparatus and Rough ER
What process do MHC class I proteins undergo before leaving the ER?
Sites with various proteasome-derived peptide fragments bind to MHC class I proteins.
What is the function of T lymphocytes towards cells with unfamiliar MHC epitopes on tissue grafts?
Eliminate them as potentially tumorigenic, infected, or abnormal cells.
Which cells display MHC class I molecules presenting self-antigens?
All nucleated cells
Where are MHC class II proteins synthesized and transported to the cell surface?
Mononuclear phagocyte system
What is the role of MHC class II proteins in antigen presentation?
Signal T lymphocytes against pathogenic cells
What type of rejection occurs in homografts (allografts)?
Immunological rejection
Which type of graft involves identical twins?
Isografts
Which cells are considered 'professional' antigen-presenting cells (APCs)?
Dendritic cells
What induces the transient expression of MHC class II on certain local cells during inflammation?
Interferon-γ
Where do progenitors of B lymphocytes mature and differentiate further?
Bone marrow
What is the main function of stem cells in adults for all lymphocytes?
Red bone marrow
What is the primary function of helper T cells?
Activate B cells into plasma cells
Which surface proteins are involved in activating different responses to antigens for B and T cells?
CD4 and CD8
How do cytotoxic T cells recognize antigens on foreign or virus-infected cells?
Via interaction with MHC class I molecules
What is the primary role of fibroblastic reticular cells in lymphoid tissue?
Produce reticulin fibers
Which type of lymphocytes bind antigens directly?
B cells
What is the function of cytotoxic T lymphocytes (CTLs) when activated?
Kill foreign or virus-infected cells
Which lymphocytes are characterized by the presence of CD8?
Cytotoxic T cells
What is the main function of fibrous reticulin fibers in lymphoid tissue?
Support lymphocytes
How do T lymphocytes recognize antigenic epitopes?
Via surface protein complexes T-cell receptors (TCRs)
What is the primary role of naive lymphocytes in newborn infants?
Recognize antigens
Which cells release perforins and granzymes to trigger apoptosis?
Cytotoxic T cells
What is the function of Regulatory T cells (Tregs)?
Inhibiting specific immune responses
Which type of T lymphocytes contain γ (gamma) and δ (delta) chains in their TCRs?
γδ T lymphocytes
Where do γδ T cells primarily migrate to in the body?
Epidermis and mucosal epithelia
What happens to B cells when BCRs bind an antigen?
Endocytosis of the antigen
What stimulates several cycles of cell proliferation in B lymphocytes?
Cytokines from helper T cells
What type of cells have long filamentous processes and interact with B lymphocytes in secondary lymphoid tissues?
Follicular dendritic cells (FDCs)
What characterizes secondary nodules in secondary lymphoid tissues?
Presence of large lymphoblasts in germinal center
What is the primary function of plasma cells derived from activated B cells?
Secrete antibodies that bind specific epitopes
How are memory B cells different from plasma cells?
Memory B cells are long-lived and responsible for rapid antibody production upon reinfection.
Explore the maturation and circulation of B and T cells through primary and secondary lymphoid organs. Understand how lymphocytes continuously recirculate through connective tissues, blood, and lymph. Learn about the cellular locations and microscopic details of lymphoid organs.
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