Question 1

The pattern recognition receptors on cells of the innate immune system are genetically encoded, meaning that their sequences and specificities are determined prior to the development of the individual. In contrast, the antigen receptors of B and T lymphocytes arise from a random rearrangement process that occurs differently in each lymphocyte as it develops. One potential problem entailed by the random process that generates lymphocyte antigen receptors is the possibility that:

Accepted Answer

A)  Some antigen receptors might recognize the individuals on cells or antigens 
B)  Many lymphocytes might generate antigen receptors that don't recognize anything 
C)  Many lymphocytes might generate antigen receptors that recognize multiple different pathogens 
D)  Some antigen receptors might recognize foreign tissues and lead to graft rejection during organ transplantation 
E)  Some lymphocytes might not generate functional antigen receptor proteins

Question 2

Individuals with defects in T cell development have a severe immunodeficiency disease called SCID (severe combined immunodeficiency disease). In these individuals, the absence of all T cells causes defects in both cell-mediated (T cell-based) and humoral (antibody-based) immune responses. The defect in antibody responses in SCID patients is due to:

Accepted Answer

A)  The important role of T cells in regulating B cell development in the bone marrow 
B)  The inter-dependence of T cells and B cells for the normal development of secondary lymphoid organs. 
C)  The absence of phagocytic cells needed for antibody-dependent pathogen clearance in SCID patients 
D)  The poor survival of B cells in patients with defects in their T cells 
E)  The important role of T follicular helper cells in generating protective antibody responses

Question 3

Several subsets of innate lymphoid cells (ILCs) have been identified that share their patterns of cytokine production with the known subsets of T cells. The combined activity of related ILC and T cell subsets is effective in eradicating pathogenic infections because:

Accepted Answer

A)  ILCs cannot kill the pathogen, whereas the antigen-specific T cells can kill the pathogen. 
B)  The early response of ILCs that reside at the site of infection is followed by the later more robust response of pathogen-specific T cells that migrate to the site of infection. 
C)  The ILCs activate B cells to induce antibody responses whereas the T cells are able to directly eliminate the pathogen. 
D)  The ILCs are induced to migrate from the site of infection to the draining lymph nodes where they activate the antigen-specific T cells. 
E)  The ILCs are activated to secrete antimicrobial compounds which cause them to lyse, releasing RNA and DNA that act on T cells to stimulate T cell cytotoxic activities.

Question 4

One surprising aspect of the immune system is that individuals make responses to human tissues from a different individual, causing serious problems for organ and tissue transplantation. The basis for this immune response is:

Accepted Answer

A)  The extensive polymorphism of MHC genes in the human population 
B)  The fact that transplanted tissues often carry infectious microbes into the recipient 
C)  The fact that individuals may differ in their blood group antigens (i.e., their blood type) 
D)  The presence of many antigen-presenting-cells in the transplanted tissue 
E)  The presence of many B and T lymphocytes in the transplanted tissue

Exam 1: Basic Concepts in Immunology

Several subsets of innate lymphoid cells (ILCs) have been identified that share their patterns of cytokine production with the known subsets of T cells. The combined activity of related ILC and T cell subsets is effective in eradicating pathogenic infections because:

One surprising aspect of the immune system is that individuals make responses to human tissues from a different individual, causing serious problems for organ and tissue transplantation. The basis for this immune response is: