TM Immunology

Question 1

Define antigenic determinant

Answer 1

• aka epitope
• part of antigen recognized by antibodies

Question 2

Define antigenicity

Answer 2

• “immunogenicity”
• ability of a foreign antigen to induce an immune response

Question 3

Define atypical antibody

Answer 3

• do not exist under normal conditions
• arise from blood transfusions, incompatible maternal and fetal blood group

Question 4

Define blocking antibody

Answer 4

• an antibody that does not react when combined with an antigen
• blocks other antibodies from binding to that antigen

Question 5

Define complete antibody

Answer 5

• mostly B-cell IgG
• take part in agglutination reactions after binding an antigen

Question 6

Define immune antibody

Answer 6

attach to foreign antigens (bacteria) and remove them from the body

Question 7

Define incomplete antibody

Answer 7

• mostly B-cell IgM
• do not participate in agglutination reacting after binding an antigen
• these are produced in response to a particular antigen

Question 8

Define irregular antibody

Answer 8

• non-ABO
• mostly IgG
• appear after exposure to foreign antigens

Question 9

Define isohemagglutinin

Answer 9

• naturally occurring
• ABO antibodies

Question 10

Define monoclonal

Answer 10

• antibodies that bind to the same epitope
• come from a singular lineage of WBCs

Question 11

Define naturally-occurring antibody

Answer 11

• mostly IgM (Lewis, P1, MN, ABO)
• arise from environmental stimuli/ non-RBC stimulated
• even if antigen is missing, the corresponding antibody is always present

Question 12

Define opsonin

Answer 12

• an antibody or C3b (complement) that binds to foreign bacteria or cells
• makes them susceptible to phagocytosis or complement

Question 13

Define polyclonal

Answer 13

• secreted by different B cell lineages within the body
• react against a specific antigen, but at different epitopes

Question 14

Define unexpected antibody

Answer 14

• existence in person’s serum was not anticipated before testing
• all blood groups besides ABO*
• anti-A1 of A2 individuals

*ABO is expected because ABO antibodies are always present

Question 15

Define xenoantibody

Answer 15

• an antibody produced in one species due to an antigen in another species

Eg. antibody forms to epitopes in a pig organ when transplanted to a human

Question 16

Describe the classical complement cascade

Answer 16

• initiated by pathogen/ pathogen-Ab complexes
• C1q, C1r, C1s binding to antigen-antibody complexes (IgG and IgM)
• proteins are recruited to generate C3 convertase (C4b2b)
• C3 is cleaved = C3b component binds back to C3 convertase (C4b2b) to generate C5 convertase (C4b2b3b)
• The cleaved products attract phagocytes to the site of infection and tags target cells for elimination by phagocytosis
• C5 convertase initiates assembly of the membrane attack complex (MAC)
• The MAC creates a pore on the target cell’s membrane = cell lysis and death