May 2022
Ampath | ampath.co.za
Updated Terminology and Diagnostic Structure
✅ Connective Tissue Disease (CTD)
- Formerly referred to as the ENA (Extractable Nuclear Antigen) screen
- The CTD screen now includes the following autoantibodies:
- RNP
- Sm
- SSA (Ro)
- SSB (La)
- Scl-70 (Topoisomerase I)
- Jo-1
- Centromere-B
- PM-Scl
- Mi-2
- Fibrillarin
- PCNA
- Ribosomal P-protein
- dsDNA
- RNA Polymerase III (Pol III)
- Ro-52
✅ CTD Profile Options
CTD Profile 1 (7 markers, only 6 billed):
- RNP
- Sm
- SSA (Ro)
- SSB (La)
- Scl-70 (Topoisomerase I)
- Jo-1
- Centromere-B
CTD Profile 2 (5 markers, all billed):
- PM-Scl
- Mi-2
- Fibrillarin
- PCNA
- Ribosomal P-protein
Note:
- dsDNA, RNA Pol III, and Ro-52 are included in the CTD screen, but not in Profiles 1 or 2
- dsDNA must be requested separately if indicated
- RNA Pol III is assessed on the Systemic Sclerosis Profile
- Ro-52 is included in all autoimmune profiles listed below
Other Key Antibody Testing Notes
✅ Double-Stranded DNA (dsDNA)
- Included in the CTD screen, not in the CTD profiles
- A second SLE-specific dsDNA ELISA (dsDNA complexed with nucleosome) is available and must be specifically requested
✅ Cytoplasmic Antibodies
- If cytoplasmic antibodies are identified during ANA screening:
- A cytoplasmic autoimmune profile is available for follow-up
Updated Autoimmune Profiles (Previously Called "Western Blot" Panels)
✅ Cytoplasmic Profile
- AMA-M2
- 3E (BPO)
- Ribosomal P-protein
- Jo-1
- SRP
- PL-7
- PL-12
- EJ
- OJ
- Ro-52
✅ Myositis Profile
- Mi-2α
- Mi-2β
- TIF1γ
- MDA5
- NXP2
- SAE1
- KU
- PM-Scl 100
- PM-Scl 75
- Jo-1
- SRP
- PL-7
- PL-12
- EJ
- OJ
- Ro-52
✅ Systemic Sclerosis Profile
- Scl-70 (Topoisomerase)
- Centromere A
- Centromere B
- RNA Pol III (RP11 & RP155)
- Fibrillarin
- NOR-90
- Th/To
- PM-Scl 100
- PM-Scl 75
- KU
- PDGFR
- Ro-52
✅ Autoimmune Liver Profile
- AMA-M2
- 3E (BPO)
- Sp100
- PML
- Gp210
- LKM1
- LC1
- SLA/LP
- Ro-52
✅ ENA Profile
More comprehensive than CTD Profiles 1 and 2. Includes 16 autoantigens:
- Sm/RNP
- Sm
- SSA (Ro)
- Ro-52
- SSB (La)
- Scl-70
- PM-Scl
- Jo-1
- Centromere B
- PCNA
- dsDNA
- Nucleosome
- Histone
- Ribosomal P-protein
- AMA-M2
- DFS-70
Streptavidin in Immunoassays
- Ampath's primary autoantibody test platforms use streptavidin-biotin systems to enhance antibody detection.
- Some patients have streptavidin antibodies, which can cause false positives.
- No commercial test exists to detect streptavidin antibodies.
- Solution: Request an ENA profile (line immunoassay), which is streptavidin-free.
- All autoimmune profiles listed above are streptavidin-free.
Implementation
- These changes were implemented from 23 May 2022
- During the transition, result commentary will guide clinicians
- Updated autoimmune request forms are available
- Customisable electronic request forms can be ordered through your area marketer
Conclusion
Ampath’s goals with these updates:
- Simplify CTD diagnostic workflows
- Contain patient costs
- Offer additional testing only when indicated
- Enable request of individual antigens when needed
- Support access to international send-away testing for rare autoantibodies
- Stay aligned with current best practices in autoimmunity diagnostics
📌 For support, profile selection, or advanced testing enquiries, contact your local Ampath pathologist.
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