55 topics with concise breakdowns: definitions, key facts, and class questions.
This section focuses on the subtle mechanisms of acquired immunity. We will examine the entire life cycle of lymphocytes: from their origin in the bone marrow and thymus to recirculation and migration to the lymph nodes, spleen, and mucous membranes.
The foundation of the adaptive response is exquisite specificity. You will learn how the colossal diversity of T- and B-cell receptors is generated (including the mechanisms of V(D)J recombination), how antigen-presenting cells process and present antigens in association with major histocompatibility complex (MHC) molecules, and how the immunological synapse forms during T-cell activation.
What are the most frequent questions in class? Instructors traditionally demand a deep understanding of the processes of positive and negative selection of lymphocytes, mechanisms of somatic hypermutation, and isotype switching. Make sure to master the differences between thymus-dependent and thymus-independent antigens, the role of co-stimulatory molecules and cytokines. Also, do not miss the topic of hybridomas and monoclonal antibodies—this is not only a popular exam question, but also the basis for understanding modern biological therapy.
What is the essence of the clonal selection theory?
Lymphocyte clones bearing receptors for all possible epitopes are spontaneously generated in the body. The antigen does not "teach" the cell to build an antibody from scratch, but merely selects and stimulates an already prepared complementary clone.
What is the main difference between cytotoxic T cells and NK cells?
NK cells belong to innate immunity, lack clonal specificity and memory, and recognize stress-induced molecules. Cytotoxic T cells possess strict antigen specificity, require presentation via MHC class I, and form long-term immunological memory.
What is the difference between Fab and Fc fragments?
The Fab fragment is responsible for specific antigen binding (contains variable domains). The Fc fragment is the constant "tail" region of the molecule, which is recognized by receptors on macrophages and neutrophils and triggers effector reactions.
What is an "internal image of the antigen"?
This is a situation where the active site of an anti-idiotypic antibody spatially resembles the original antigen. However, complete identity does not occur due to differences in geometric shapes: the antigenic epitope is convex, while the antibody binding site is concave.
What is the difference between serum and membrane IgM?
Membrane IgM is a 7S monomer, whereas serum (secreted) IgM exists as a 19S pentamer.
Does the CD3 complex participate in antigen recognition?
No, CD3 molecules are incapable of recognizing antigens. Their sole, yet critically important function is to transmit a chemical signal inside the lymphocyte after the TCR has bound to the ligand.
Master the entire topic in the "Immunology" course
This is a summary. The course covers everything tested in classes and exams.
723 pages of study guides for all topics
Assignments and quizzes after every topic — just like in a colloquium