Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
Humoral Rejection
Henny OttenDepartment of Immunology
HLA Class-I and -II
Binding of peptides to HLA
HLA-restriction
Polymorphism of HLA atpositions near interaction withTCR and peptide
S. Marsh, 2008
Polymorphism of HLA
Frequency of alleles
Many allele variants per locus
Linkage disequilibrium
Combinations of alleles
ABC
Class-I
DRBDRADQB1DQA1DPB1DPA1
Class-II
Proteinvariants
Proteinvariants
390711210
4512
5725
11214
HLA-Antibodies
Pregnancy - Antigens from the father
Transfusion - leukocytes
Transplantation - HLA mismatches donor
Contra-indication for transplantation
Decreased chance finding suitable donor
Some patients have antibodies against >85% of potential donors
Current antibody status ~ non-current
Histocompatibility in Organ Transplantation
Purpose - prevention of rejection
Matching - HLA class-I: A and B (and C) antigens- HLA class-II: DR (and DQ) antigens- ABO
HLA-antibodies - sensitization- allo- vs autoantibodies- screening- cross-match
Hyperacute rejection of a renal allograft
monomer
most prevalent Ig in serum,
longenst halflife (23 days)
4 subklasses:
IgG1: 70%
IgG2: 20%
IgG3: 7%
IgG4: 3%
IgG
2 forms
1. Membrane bound monomer
= B cel antigen receptor
2. free as pentamer (a lot in the circulation)
> 10 binding sites!
produced during primairy immune response
IgM
IgMIgM & & IgGIgG antibodiesantibodies
Primary & secondary immune responsePrimary & secondary immune response
- specificity
biologicalactivitity
=effector function
Antibodies = multifunctional adaptors
- diversity
Hyperacute Rejection
Types of Humoral Rejection (I)
Occurs when the recipient has previously been sensitized to the donor tissue
Caused by complement fixation of pre-existing antibodies against thetransplanted tissue, causing damage and extensive necrosis
Rejection starts within minutes of reperfusion
Relatively rare now with routine crossmatching of donor/recipient serum
Acute Humoral Rejection
Chronic Humoral Rejection
Complement mediated Damage
IgG1, IgG3 and IgM
Types of Humoral Rejection (II)
Hyperacute Rejection
Characterized by the production of anti-class-I and –II antibodies against the donor tissue (C4D on PTC)
Rapid loss of graft function (days), any time after transplantation
Treatment involves IVIG, plasmapheresis and/or rituximab (=anti-CD20)
Acute Humoral Rejection
Chronic Humoral Rejection
C4D staining of peritubular capillaries
Positive Negative
Types of Humoral Rejection (III)
Hyperacute Rejection
Transplant glomerulopathy is strongly associated with circulating antibodies to donor HLA class-II antigens and a poor prognosis
The "ABCD tetrad: The combination of alloantibody, basement membrane multilamination, C4d, and duplication of the GBM
Outcome and optimal therapy not yet defined
Acute Humoral Rejection
Chronic Humoral Rejection
Stages of Humoral Alloreactivity
Crossmatch & HLA antibody screening
Patient serumT-cells: class-IB-cells: class-II Complement Interpretation
Limitations of CDC
Cells have more than 1 type of HLA-antigen on their surface
Literature: positive class-I crossmatches (T-cells) are o.k.50-75% positive class-II crossmatches (B cells) are incorrect!
Interpretation heavily depends on quality of the cells
A1, A2, B7, B8
Positive
A23, A24, B13, B15
Negative
A1, A24, B13, B15
A1, A2, B13, B15
A1, A2, B7, B15
Patient sera usually contain more than 1 HLA-specificity
Luminex
Antibody Screening by Luminex
Single HLA-antigen Beads
MF
I
Sensitivity of HLA Antibody Assays
100,000 1000
LuminexBeads withsoluble HLAantigens
FACSXmatch Tor B cells
Microarray/ELISAWith solubleHLA antigens
AHG-CDCT cellXmatch
CDCT or B cellXmatch
ComplementEnzymeImmunofluorescence
Limits of detection: molecules of antibody