Resolution of T Cell Lymphopenia in a Term Infant with Absent TRECs on Newborn Screen
Monday, March 7, 2016
South Exhibit Hall H (Convention Center)
Peter Mustillo, MD FAAAAI, Rosemary Hage, Margaret Redmond, MD
Rationale: Screening for severe combined immunodeficiency(SCID) in the United States(US) using T- cell receptor excision circles(TRECs) began in 2008 and is currently operating in 26 US states*, the District of Columbia, and the Navaho Nation. This screening is facilitating early identification of SCID and other syndromes with T cell lymphopenia.

Methods: TRECs screening performed by the Ohio Department of Health Laboratory.

Results: SM is a term female whose newborn screen demonstrated no detectable TRECs x2. Initial flow cytometry revealed a CD3 count of 1171 cells/cu mm, CD4 count 979, CD8 count 192, CD19 606 and CD56/CD16 180.  Initial CD3CD45RA was 70% and CD3CD45RO 28%. T cell function studies revealed normal mitogen proliferation but low anti-CD3 proliferation.   Repeat newborn screen at one month confirmed absent TRECs.  TCR-v-beta repertoire was normal.  Subsequent diagnostic workup for 22q deletion syndrome, HIV, ataxia telangiectasia and bare lymphocyte syndrome was negative.  Next-generation SCID sequencing was also negative.  IgG/A/M levels were normal at 9 months.  CD3, CD4 and CD8 counts normalized by 12 months, though anti-CD 3 proliferation remained low.  Repeat newborn screen testing at one year revealed TRECS in the normal range.  Patient is thriving and developing normally at 14 months with no recurrent or serious infections.

Conclusions: As more states adopt TRECs screening for SCID on the newborn screen, it is important to be aware that even some term infants with no detectable TRECs may have resolution of T cell lymphopenia and no evidence of a serious immune deficiency.