Question | Answer |
What are the antigens primarily responsible for the rejection of tissues, cells, or organs from genetically dissimilar donors? | histocompatibility antigens |
What are the histocompatibility antigens the ones that are responsible for the greatest immune response? | the ones from MHC major histocompatibility complex |
Where is MHC located in humans? | chromosome 6 |
What is the function of the MHC genes? | they encode cell surface proteins that are critical to the immune response that discriminate self from non-self |
What is the critical role of the MHC gene in every day immune response? | present peptides to T cells |
Class 1 or Class 2 genes are what in chromosome 6? | MHC genes |
How many different Class one genes are there? | 3; A,B, and C |
Class 2 MHC genes will encode what, and how many different types? | DP, DQ and DR, there will be two different types alpha and beta |
Where do we find class 1 MHC molecules? | on the surface of all nucleated cells so every cell in the body other than erythrocytes |
What do class 1 MHC molecules do? | they have a binding pocket that contains a peptide so the T cell sees the binding pocket with the peptide its about 7that the T cell will recognize |
What do class 2 MHC molecules do? | encode DP,DQ, DR genes of which there are 2 alpha and beta for each one |
Where do you find class2 MHC molecules? | primerarly on the surface membrane of antigen presenting cells (APCs) dendritic cells, macrophages ect. |
What do class 2 MHC molecules do? | same thing as class 1 MCH they have a pocket with a peptide |
What is an allele? | one of several alternate forms of a gene at a single locus that controls a particular characteristic |
Example of Class 1 alleles are HLA-A, HLA-B, and HLA-C, What does HLA stand for and how many known alleles are there for each of these examples? | HLA = human leukocyte antigen, 218,439,96 |
What type of alleles do class 1 gene encode for T cells? | HLA-A, HLA-B, HLA-C |
Which alleles do class 2 genes of T cells encode? | HLA-DR, HLA-DQ, HLA-DP, each with an alpha and beta form |
Why is it important to have all this variablity encluded in the alleles? | each pocket can have a range of peptides in there, each allele will have a different range of peptides it can display, so that some important peptide will be displayed so the T cell can recognize something from almost every pathogen you may encounter |
Haplotype is what and how many do we have? | a group of all the genes you inherit on one chromosome, 2 one from mom and one from dad |
What is the crucial function for HLA proteins? | to present peptides to T-lymphocytes |
What is the beta 2 microglobulin always expressed with? | class 1 protein |
In the peptide binding cleft what do you have? | peptide |
In general CD8 positive T cells (killer cells) will only recognize peptide on what type of MHC molecule? | class 1 MHC molecules |
Where are class 1 MHC molecules found? | on all nucleated cells |
In general CD4 positive T cells (regulator, helper cells) will only recognize peptide on what type of MHC molecule? | class 2 MHC molecules |
Where are class 2 MHC molecules found? | on antigen presenting cells |
Where does the binding of CD4 to its MHC molecule happen? | in the lymphoid tissue |
What is relative risk? | the chance an individual with disease associated HLA antigen has of developing the disease compared with an individual who lacks that antigen |
If you find the HLA allele DR2 what disease and relative risk would your patient have? | multiple sclerosis, 4 |
If you find the HLA allele DR2/3 what disease and relative risk would your patient have? | SLE, 4 |
If you find the HLA allele DR3 what disease and relative risk would your patient have? | Sjogren’s syndrome, 10; and Type 1 diabetes, 5 |
If you find the HLA allele DR4 what disease and relative risk would your patient have? | Rheumatoid art, 6 |
If you find the HLA allele DR3/4 what disease and relative risk would your patient have? | Type 1 diabetes, 20 |
If you find the HLA allele DR27 what disease and relative risk would your patient have? | Ankylosing spondylitis, 90 |
What is the role of MHC in organ tissue graft rejections? | recognition of non-self MHC by recipient T-cells is the major initiating factor for allograft rejection, make sure to try and match MHC to minimize rejection |
The drug Cyclosporine does what, and what role does it play in transplantation? | inhibits T cell activation, inhibits some cytokine production and inhibits the immune response that rejects organ transplants |
What are serologic tests to detect HLA antibodies in transplant cadidates? | antibody screening |
What technique uses PCR amplification and DNA sequencing? | DNA typing |
What is the purpose of the technique known as cross match? | to detect antibody in the patient’s serum that react against HLA antigens of the potential donor |
What characteristics distinguish class 1 from class 2 HLA proteins? | location, class 1 on all cells Class 2 on antigen presenting cells; total proteins encoded, Class 1 encodes one, class 2 encodes 2 an alpha and beta; molecules presented to, Class 1 to CD8, class 2 to CD4 |
How can HLA make up influence immune response to particular pathogen? | each persons HLA make up is different, if unable to display peptide to pathogen then unable to recognize and fight off |