A Case of "Abnormally Abnormal" Hypoxic Ventilatory Responses: A Novel NPARM PHOX 2B Gene Mutation.

ABSTRACT: Congenital central hypoventilation syndrome (CCHS) is a rare disorder associated with dysregulation of the autonomic ventilatory response to hypoxia and hypercarbia usually caused by polyalanine repeat expansion mutations in the PHOX 2B gene. Non-polyalanine repeat mutations (NPARM) represent approximately 10% of cases, and usually require continuous ventilation during sleep, although our knowledge of disease progression is limited. Here we present a case with a novel NPARM CCHS mutation associated with a premature stop codon for the PHOX 2B protein. Despite the type of the mutation, patient management with supplementary oxygen has been sufficient. Experience from our case may help when counseling parents.

Initial depletion of regulatory T cells: the missing solution to preserve the immune functions of T lymphocytes designed for cell therapy.

We investigated the causes of the altered functionality of T cells cultured under conditions designed for cell and gene therapy and the strategies to prevent their defects. We first showed that human T cells cultured for 6 days with anti-CD3 +/- anti-CD28 antibodies and interleukin-2 presented a 50% decrease of their proliferative responses to allogeneic or recall antigens. Similarly, day-6 cultured murine T cells completely lost their capacity to reject allogeneic skin grafts and to provoke graft-versus-host disease (GVHD) when infused into irradiated semi-allogeneic mice. Interestingly, injection of higher amounts of cultured T cells restored GVHD induction. Moreover, depletion of CD25+ cells prior to T-cell cultures can prevent these deficiencies both in mice and humans. Therefore, we demonstrated that culture conditions used for T-cell therapy preferentially activated and expanded regulatory T cells (Treg's). Thus, we showed that dividing cells sorted from T-cell cultures strongly suppressed the proliferation of autologous T cells in response to allogeneic stimulation. An increased detection of Foxp3 at mRNA and protein levels in the cultures confirmed the Treg expansion. Overall, we demonstrate that T-cell cultures promote Treg expansion over effector T cells, leading to deleterious immune functions, and that this imbalance can be prevented by an initial depletion of CD25+ cells.