Autologous Serum Skin Test

12 Apr 2019
Autologous Serum Skin Test

Question
Is the autologous serum skin test useful in clinical practice?

Answer
By Luis Felipe Chiaverini Ensina, MD

The autologous serum skin test (ASST) is defined as an in vivo test to assess autoreactivity.  The test involves an intradermal injection of autologous serum.  The frequency of a positive ASST (ASST+) is about 45% in patients with chronic spontaneous urticaria (CSU).  However, the prevalence of an ASST+ is high in non-CSU patients with allergic or non-allergic respiratory symptoms, ranging from 30-50% in adults and up to 80% in children (1).

To avoid unreliable data when performing the ASST, special attention should be given to the technique, timing, and reading.  Antihistamines should be stopped at least 2-3 days before the test.  A standardized methodology to perform the test is well described and recommended in an EAACI’s task force consensus report (1). 

The ASST negative predictive value is reported to be 82.5± 14% when used as a marker for functional antibodies against IgE or the high-affinity IgE receptor (FceRI); thus, a negative result indicates the absence of these autoantibodies (2).  An ASST+ has been proposed to be included as one of the requirements to diagnose chronic autoimmune urticaria (3).  

A recent metanalysis of studies in Asian patients showed an association of ASST+ with higher levels of total serum IgE and thyroid autoantibodies.  Furthermore, it was also observed a higher urticaria activity score in 7 days (UAS7) and high risk of angioedema in patients with ASST+, suggesting an association of test positivity and disease severity (4).  On the other hand, a negative ASST has demonstrated to be a good predictor for reaching urticaria remission within two years (5). 

In conclusion, the ASST is an in vivo test that requires specific structure and technique to be performed.  It may help to demonstrate for the patients the autoimmune nature of their disease.  Its association with disease severity and prognosis it is not decisive but can be useful in determining the best therapeutic approach.

References

1. Konstantinou GN, Asero R, Maurer M, Sabroe RA, Schmid-Grendelmeier P, Grattan CEH. EAACI/GA(2)LEN task force consensus report: the autologous serum skin test in urticaria. Allergy.  2009; 64:1256–68.
2. Sabroe RA, Grattan CE, Francis DM, Barr RM, Kobza Black A, Greaves MW. The autologous serum skin test: a screening test for autoantibodies in chronic idiopathic urticaria. Br J Dermatol. 1999;140:446–52.
3. Konstantinou GN, Asero R, Ferrer M, Knol EF, Maurer M, Raap U, et al. EAACI taskforce position paper: evidence for autoimmune urticaria and proposal for defining diagnostic criteria. Allergy.  2013; 68:27–36.
4. Niu XL, Zhu LL, Shi MH, Zhang YJ, Gao XH, Qi RQ. Association of positive and negative autologous serum skin test responses with clinical features of chronic spontaneous urticaria in Asian patients: A systematic review and meta-analysis. Exp Ther Med. 2019;17:2603–13.
5. Boonpiyathad T, Sangasapaviliya A. Autologous serum and plasma skin test to predict 2-year outcome in chronic spontaneous urticaria. Asia Pac Allergy. 2016;6:226–35.

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