We recently read an article published in The Journal of Immunology by Enioutina et al. (1) and found an experimental procedure we believe should be discussed. In this article, as well as in many others by the same authors—also in The Journal of Immunology and other renowned journals (2, 3)—serum-specific Abs are quantified by ELISA. According to our knowledge, this could be a misconception, given that we believe ELISA cannot be used for that purpose.

Polyclonal antisera raised against the same Ag could differ in both the affinity and the concentration of the specific Abs. The main premise of quantification is that sample and reference standards must share all biological and physicochemical properties because the analyte concentration is the only unknown factor. The authors have not declared what they have used as the “reference standard,” not in the article that gives rise to this letter, nor in the others published before. Considering that the samples are polyclonal antisera, we believe there is no way to construct such a standard curve that allows expressing the results as a concentration of specific Igs. Therefore, we think that the only reliable information that can be obtained from this sort of assay is a “relative potency” value, commonly expressed as titer of specific Abs.

We certainly think that this issue does not affect the quality of the work by Enioutina et al., but we do think that the quantitative aspects deserve further discussion.

1
Enioutina
E. Y.
,
Bareyan
D.
,
Daynes
R. A.
.
2011
.
A role for immature myeloid cells in immune senescence
.
J. Immunol.
186
:
697
707
.
2
Enioutina
E. Y.
,
Visic
D. M.
,
Daynes
R. A.
.
2002
.
The induction of systemic and mucosal immunity to protein vaccines delivered through skin sites exposed to UVB
.
Vaccine
20
:
2116
2130
.
3
Enioutina
E. Y.
,
Bareyan
D.
,
Daynes
R. A.
.
2009
.
TLR-induced local metabolism of vitamin D3 plays an important role in the diversification of adaptive immune responses
.
J. Immunol.
182
:
4296
4305
.