Complement-Dependent Cytotoxicity (CDC)
Definition
A serological HLA typing method in which test lymphocytes are incubated with HLA-specific antibody and then with complement. If the antibody binds, complement activation lyses the cell. Cell death is detected by dye uptake (trypan blue or eosin-Y) under a microscope. Positive wells (dead cells) identify which HLA antigens are present.
- Abbreviation
- CDC
- Field
- Serological HLA typing
- Reagents
- HLA-specific antibody plus complement
- Detection
- Dye uptake (trypan blue or eosin-Y) under microscope
- Readout
- Cell death indicates the antigen is present
Common questions
Has CDC typing been largely replaced in modern forensic relationship testing?+
Yes. Molecular, DNA-based HLA typing methods have largely superseded serological CDC typing in routine forensic and transplant laboratories because they are more precise and do not depend on viable lymphocytes, though CDC crossmatching still has a role in some transplant compatibility testing.
Why is cell viability important before running a CDC assay?+
The assay depends on complement being able to lyse a living cell after antibody binding, so if the starting lymphocytes are already dead or damaged, the dye uptake readout becomes unreliable and can produce a false positive for antigen presence.
Related terms
- HLA Haplotype
- The specific combination of HLA alleles inherited as a block on one copy of chromosome 6. Because HLA loci are tightly linked,...
- HLA (Human Leukocyte Antigen)
- Cell-surface glycoproteins encoded by the major histocompatibility complex (MHC) on chromosome 6p21. They present peptide antigens to T cells and are the...
- Linkage Disequilibrium
- The non-random association of alleles at different loci within a population. Certain HLA allele combinations (e.g., HLA-A1 with HLA-B8 with HLA-DR3) occur...
- Paternity Index (PI)
- A likelihood ratio that compares the probability of the observed serological profile if the alleged father is the biological father to the...
- Sequence-Specific Primer PCR (SSP)
- A molecular HLA typing method that uses primer pairs designed to amplify only if a specific allele sequence is present. Results are...