Interesting papers in PID

Articles review - July 2014

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by Andrew Gennery

Three interesting studies examining outcome of haematopoietic stem cell transplantation (HSCT) for severe combined immunoderficiency (SCID) have been recently published:

Pai and colleagues from the Primary Immune Deficiency Treatment Consortium (PIDTC) have just published the first US-wide retrospective study of outcome for HSCT for patients with SCID transplanted between 2000-20091. This article is important for a number of reasons:

  • It is the first North American-wide multi-centre study looking at outcome of HSCT for SCID.
  • It analyses outcomes since 2000, and therefore is relevant in the ‘modern era’ of HSCT
  • It is the first report documenting outcome of HSCT since the advent of Newborn Screening for SCID

As might be predicted, survival was best for those transplanted before 3 months of age who were infection-free. Interestingly, in those transplanted at an older age – survival was similar in those who had had infection, as long as it had cleared.

Dvorak and colleagues have published a joint PIDTC-IEWP study comparing outcomes of transplant for SCID patients using matched unrelated donor or matched sibling donor infusions2. Although most patients undergoing unrelated donor HCST achieved donor T-cell engraftment, similar to that achieved for sibling donors, the estimated 5-year overall and event-free survival were worse for unrelated donor recipients with higher incidences of Grade II-IV acute and chronic GVHD. Matched sibling donor recipients were more likely to achieve B-cell reconstitution.

Finally, Hassan and colleagues3 report on a retrospective UK study to determine if SCID phenotypes indicate host permissiveness to donor cell engraftment following non-conditioned HSCT. A detailed analysis of T- and B-cell immune reconstitution and donor chimerism was compared between the NK+ and NK- forms of SCID in almost 80 patients. Survival was better in matched sibling donor/matched family donor transplants compared with alternative donors and better in NK- rather than NK+ SCID with superior long-term recovery of CD4 T-cell immunity.  Significantly more children with NK+ SCID required additional transplantation procedures.

  1. Pai S-Y, Logan BR, Giffith LM et al. Transplantation Outcomes for Severe Combined Immunodeficiency, 2000–2009. N Engl J Med 2014;371:434-46.
  2. Dvorak C, Hassan A, Slatter MA, et al. Comparison of outcomes of hematopoietic stem cell transplant without chemotherapy conditioning using matched sibling and unrelated donors for treatment of SCID. J Allergy Clin Immunol 2014 (in press)
  3. Hassan A, Lee P, Maggina P, et al. Host natural killer immunity is a key indicator of permissiveness for donor cell engraftment in patients with severe combined immunodeficiency. J Allergy Clin Immunol 2014;133:1660-6.