lettersNK cell: an unforgettable lymphocyte (comment on “Delayed presentation of severe combined immunodeficiency due to prolonged maternal T cell engraftment”) Luis Ignacio Gonzalez-GranadoMD Luis Ignacio Gonzalez-Granado Pediatrics and Immunodeficiency Hospital, 12 Octubre, Madrid, Spain Search for more papers by this author Email the corresponding author at [email protected] Published Online:7 Apr 2011https://doi.org/10.4103/0256-4947.78209SectionsPDF ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail AboutIntroductionTo the Editor: I read with great interest the article by Al-Muhsen “Delayed presentation of severe combined immunodeficiency due to prolonged maternal T cell engraftment” in the May/June 2010 issue of the journal.1 I do really appreciate the contribution to the knowledge of maternal T cell engraftment in severe combined immunodeficiency (SCID). However, I would like to make some comments.Antibody responses are not needed when SCID is suspected. Immunoglobulin replacement therapy does not preclude this assessment, for instance, regarding antibodies agains S Typhi upon vaccination, as titers are not generally present in donors.2 Isohemaglutinins—a natural source of antibodies of type IgM—could also be measured in spite of immunoglobulin replacement (where only IgG is administered).The author state a T-B+ phenotype. However, as can be seen in [Table 1] (see reference 1), CD16-56 (the marker for natural killer [NK] cells) are below the normal range. So we can affirm the patient presented a T low B+ NK low (I say low because we use “-” when the lymphocyte subset is definitely absent). Moreover, a phenotype with decreased T and NK cells is strongly suggestive of cytokine receptor common gamma chain (gc) (or CD132) deficiency. This comprises for 2 out of 3 cases of SCID (also known as X-linked SCID). There are well established criteria by the European Society For Primary Immunodeficiencies (ESID)3The genes sequenced (RAG1/2, Artemis) show a different lymphocyte subset phenotype: T-B-. This is because the failure precludes functional V(D)J recombination that finally lead to the development of T cell and B cell surface receptors (TCR and BCR). But this does not affect NK cells. In this last case, we propose radiosensitivity tests in fibroblasts, as an easy way to guide a cheaper and faster gene sequencing (SCID with radiosensitivity are caused by defects in the nonhomologous end-joining (NHEJ) DNA repair pathway: Artemis, DNApKcs, DNA ligase IV and XLF).4CD40L deficiency (hyper IgM syndrome) was ruled out by cytometry. This is neither necessary nor reliable. CD40L should nor be considered within the differential diagnosis as IgM is absent. There is general agreement that CD40L deficiency is not ruled out in many cases, so going straightforward to gene sequencing is the most common approach.ARTICLE REFERENCES:1. Al-Muhsen SZ. "Delayed presentation of severe combined immunodeficiency due to prolonged maternal T cell engraftment" . Ann Saudi Med. 2010; 30:239-42. Google Scholar2. In: Ferry BL, Misbah SA, Stephens P, Sherrell Z, Lythgoe H, Bateman E , et al.. "Development of an anti-Salmonella typhi Vi ELISA: assessment of immunocompetence in healthy donors" . Clin Exp Immunol. 2004; 136:297-303. Google Scholar3. "Diagnostic criteria for Primary Immunodeficiencies from the European Society For Primary Immunodeficiencies (ESID)" . Last accessed on 2010 Apr 18Available from: http://www.esid.org/workingparty.hp?party=3&sub=2&id=73#Q18. Google Scholar4. In: Ege M, Ma Y, Manfras B, Kalwak K, Lu H, Lieber MR , et al.. "Omenn syndrome due to ARTEMIS mutations" . Blood. 2005; 105:4179-86. Google Scholar Previous article Next article FiguresReferencesRelatedDetails Volume 31, Issue 2Mar–Apr 2011 Metrics History Published online7 April 2011 InformationCopyright © 2011, Annals of Saudi MedicineThis is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.PDF download