16. HLA System and Graft Rejection Flashcards
Which HLA genes code for the MHC Class I antigens?
HLA-B, HLA-C, HLA-A
Which HLA genes code for the MHC Class II antigens?
HLA-D
Which class of MHC antigens are found on almost all cell types?
MHC Class I antigens
Which class of MHC antigens are found only on antigen presenting cells?
MHC Class II antigens
Suppose a child who has the HLA haplotypes, A3 B11 Cw8 Dw12 and A11 B27 Cw5 Dw9, has a mother with the haplotypes, A25 B37 Cw2 Dw8 and A11 B27 Cw5 Dw9. What HLA alleles must the child’s father have?
Father must have the HLA haplotype: A3 B11 Cw8 Dw12
The HLA system is highly polymorphic. What does this mean? What advantage does polymorphism have for the human population?
- many alternate forms of the gene or alleles exist at each locus. Ex: There are many different type of HLA-A (etc.)
- this gives variablity to the population
What type of graft is a kidney transplant between a father and his daughter?
Allograft
What type of graft is a heart valve transplant from a pig to a human?
Xenograft
What immune reaction is responsible for the rapid response seen in hyperacute rejection of a graft?
Antibody mediated immune response (Humoral) due to pre-formed antibodies
What types of T cells are involved in cell-mediated immune responses of graft rejection, and which antigens are they directed against?
- T helper 1 recognizes MHC Class II Ag
- Cytotoxic T cell recognizes MHC Class I Ag
Of the following types of grafts, which one(s) could cause graft vs host disease- kidney transplants, heart transplants, bone marrow transplants - and why?
Bone marrow transplants because it contains donor immunocompetent T cells.
Why is HLA typing not required for corneal transplants in the eye?
The cornea is an immunologically privileged site characterized by the absence of lymphatic vessels, this prevents exposure to foreign antigens of the graft.
