in terms of timeline, what are the important differences between primary and secondary immune responses?
primary is immediate and secondary is learned and later
primary response doesn't change but adaptive does
primary immune response to a pathogen
a small number of pathogen-specific cells
delay before specific antibodies are made
starts with IgM of low to medium affinity
high threshold of activation
delay before effector T cells are activated and enter infected tissues
innate immunity works alone until an adaptive response is activated and ongoing
secondary immune response to a pathogen
a large number of pathogen-specific cells
specific antibodies are already present
antibodies are isotype-switched and of high affinity
low threshold of activation
effector T cells are present and activated in the infected tissue
what are the important cells of immunological memory?
long-lived plasma cells
memory B cells
memory T cells
what are the important distinctions between long-lived plasma cells and memory B cells?
LLPCs live a longe time and do NOT express BCR and do NOT divide
what role does FcyR2B(1) have in the regulation of B cells and B cell memroy?
naive B cells express FcyRB(1)
IgG --> FcyR2B(1) engagement shuts down naive B cells
what is the hemolytic disease of newborn?
also called eryhtoblastosis fetalis
RhD- mother gives gives birth to RhD+ child
aRhD antibodies from mother react against RBCs of newborn
first pregnancy is mainly IgM which does not cross the placenta
subsequent pregnancies invoke a secondary immune response which does not cross the placenta
what is rhogam? how does it prevent erythroblastosis fetalis?
a medication given to an Rh-negative pregnant person with an Rh-positive fetus to prevent erythroblastosis fetalis. It works by providing external Rh-positive antibodies to the mother's blood, which prevents her immune system from detecting the fetal Rh-positive blood cells as foreign and creating its own antibodies. This stops the mother's immune system from attacking the fetus's red blood cells in a future pregnancy
what is CD45RA?
CD45 is tyrosine phosphatase necessary for T cell activation
CD45RA is a 'bigger' molecule and doesn't interact easily with the TCR
what is CD45RO?
via alternative splicing, CD45RO has 381 fewer amino acids
because of its smaller size, it can more easily interact with the TCR and therefore the T cell activation threshold
what are the three types of memory T cells?
central, effector, and resident
central memory
circulate between blood, lymph, and secondary lymphoid tissue
effector memory
circulate between blood, lymph, and non-lymphoid tissues
resident memory
based in non-lymphoid tissues; for rapid response
activation of T cells leads to:
metabolic reprogramming; mediated by mTORC1
cell division while T cell still attached to APC
what is antigenic original sin?
having a secondary response blocks the primary response of the other strains and leads to lack of secondary response development for those strains
what is the importance of cross-reactivity and cross-protection?
cowpox and smallpox viruses share some surface antigens
immunization with cowpox induces antibodies against cowpox surface antigens
antibodies made against cowpox bind and neutralize the smallpox virus