Which T-cell immunodeficiency findings are characteristic of cartilage-hair hypoplasia (CHH)?

Updated: Aug 06, 2019
  • Author: Alan P Knutsen, MD; Chief Editor: Harumi Jyonouchi, MD  more...
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Answer

Immunologic dysfunction occurs in approximately 86% of patients with cartilage hair-hypoplasia. [23, 32] Notarangelo et al [14] and Ip et al [12]  reported on the heterogeneity of the immunodeficiency. The immunodeficiency predominantly affects T-cell immunity.

Lymphopenia and decreased CD3+, CD4+, and CD8+ T cells present in early infancy. There may be a selective decrease of CD8+ T cells. Skewing of TCRab repertoire may be present.

T cell lymphoproliferative responses to mitogens such as phytohemagglutinin ([PHA], concanavalin A [Con A], and pokeweed mitogen [PWM] and to antigens such as Candidaalbicans and tetanus toxoid may be decreased.

Delayed-type hypersensitivity (DTH) responses to recall antigens are absent, anergic. de la Fuente et al [33] reported decreased CD4+ CD45RA+ CD31+ –naïve T cells in patients with cartilage hair-hypoplasia. In addition, T-cell receptor rearrangement circles (TRECs) were reduced in cartilage hair-hypoplasia patients, indicating decreased thymopoiesis.

T cells from cartilage hair-hypoplasia patients also demonstrated defects in cell cycle control with reduced cell divisions and increased apoptosis.

Previous studies demonstrated decreased stimulated T-cell interleukin 2 and interferon-γ synthesis and defective CD25 expression. There also appears to be increased T cell apoptosis associated with increased expression of Fas, FAS ligand (FasL), proapoptotic Bax molecules, whereas expression of antiapoptotic bcl-2 and inhibitory of apoptosisi (IAP) molecules are reduced.


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