HLA System Flashcards
Locus of genes that encode for proteins on surface of cells that are responsible for regulation of the immune system in humans
Human leukocyte antigen system
Location of HLAs
All nucleated cells and solid tissue cells
Chromosome location of HLA genes
Short arm of chromosome 6
HLA gene inheritance
Codominant
MHC class I antigens
HLA-A
HLA-B
HLA-C
MHC class II antigens
HLA-DR
HLA-DQ
HLA-DP
HLA-DN
Functions of HLA antigens
Recognize self from non-self
Involved in immune response through antigenic stimuli
Coordinate cellular and humoral immunity
Solid organ transplant survival
Populations where combinations of alleles or genotypes can be found in expected proportions
Linkage equilibrium
Occurrence of some combinations of alleles or genetic markers in a population more often or less often than would be expected from random formation of haplotypes from alleles based on their frequencies
Linkage disequilibrium
HLA antigens found on platelets
HLA-A
HLA-B
Location of class I antigens
T cells
Most nucleated cells
Solid tissue
Location of class II antigens
B lymphocytes Monocytes Macrophages Dendritic cells Intestinal epithelium Early hematopoietic cells Epithelial cells Spermatozoa Activated T lymphs
Which HLA class is derived from exogenous proteins (proteins taken up by cell)
Class II
Which HLA class is derived from endogenous proteins (proteins made by the cell)
Class I
HLA class that interacts with T lymph’s that are CD8 positive
Class I
HLA class that interacts with T lymph’s that are CD4 positive
Class II
HLA class important for host defense against malignancy transformation and viral pathogens
Class I
HLA class that secretes immunostimulatory cytokines, important for antibody production
Class II
Testing for HLA class I molecules done by:
Microcytotoxicity testing
Sequence-specific primers
Testing for HLA class II molecules done by:
Mixed lymphocyte culture
PCR
Sequence-specific primers
HLA inheritance in which individuals share a common haplotype
Haploidentical
HLA inheritance in which individuals share no common haplotype
Haplodistinct
HLA inheritance in which individuals have exact or full-house match
HLA identical
Possibility that 2 siblings will be HLA identical
25%
Cause of absence of HLA antigens
Homozygosity at particular locus and/or to a null allele
Occurs when chromosome segments which contain genetically linked material are switched between the 2 chromosomes that are present during gametogenesis or meiosis
Crossing over
Originally identified as RBC antigens but now determined to be soluble antigens associated with plasma lipoproteins that readily absorb to RBC surfaces
Bg antigens
Bga = HLA __
HLA-B7
Bgb = HLA ___
HLA-B17
Bgc = HLA___
HLA-A28