OBJECTIVE:We have previously shown that autoimmunity following alemtuzumab treatment of multiple sclerosis can be predicted by high baseline serum interleukin IL-21 (IL-21), as measured using a now ‘redundant’ enzyme linked immunosorbent assay (ELISA). Here we ask whether currently available ELISAs have similar prognostic value.
DESIGN:Serum IL-21 from 141 individuals with relapsing remitting multiple sclerosis was measured using the now ‘redundant’ IL-21 ELISA and five further currently available kits. All patients had been treated with alemtuzumab; 61/141 had developed secondary autoimmunity.
RESULTS:The ‘redundant kit’, and one current kit, confirmed higher baseline serum IL-21 in patients with autoimmunity (542 pg/mL vs. 222 pg/mL and 53.1 pg/mL vs. 9.3 pg/mL respectively) and showed positive correlation. However, only the ‘redundant’ kit had predictive utility.
CONCLUSIONS: Currently available IL-21 ELISA kits should not be used to counsel individuals with multiple sclerosis considering treatment with alemtuzumab.
Predicting Autoimmunity after Alemtuzumab
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Azzopardi L, Thompson SA, Harding KE, Cossburn M, Robertson N, Compston A, Coles AJ, Jones JL. Predicting autoimmunity after alemtuzumab treatment of multiple sclerosis. J Neurol Neurosurg Psychiatry. 2013 Dec. doi: 10.1136/jnnp-2013-307042. [Epub ahead of print]
An ELISA that detected soluble interleukin 21 was used and was suggested to predict, in part, whether autoimmunity may develop after alemtuzumab treatment. An ELISA against interleukin 21 is may contain a capture IL-21 antibody that is stuck to plastic and a detect anti-body that has a dye attached to it. So you add blood which contains IL-21 that is bound to the capture antibody and then you add the detect antibody that can now bind to the captured IL-21 and the more IL-21 in the blood the more that is captured the more detection signal you get. You then take a known amount of IL-21 and put this in the assay and then you can work out how much is in the blood. You can make these ELISAs up or eventually a company will make a kit, which is easier to do and generally gives more consistent results. This study tests a few commercial kits and none of them performed as well as the original ELISA and they had n predictive value. There are clearly problems with the ELISAs as they are not accurately detecting the levels in the blood ~500pg/ml in one verses 50pg/ml. This paper says that you can’t use current commercial kits to predict whether you will get autoimmunity after campath. Was the original interpretation correct.
