LAUSR

methotrexate (MTX) was not used for GVHD prophylaxis. The present patient developed PES followed by severe GVHD. Both high numbers of transfused cord blood cells and GVHD prophylaxis without MTX are risk factors for PES, and PES is a risk factor for severe GVHD. Host antigen-presenting cells not suppressed by conditioning therapy may have presented host antigens to high numbers of donor T cells not suppressed by MTX, possibly leading to severe GVHD. Finally, this patient developed fatal IPS. Risk factors for IPS include GVHD and a prior history of pneumonitis. The patient had severe GVHD and PCP before CBT, which would contribute to the development of IPS. Signaling through TNF receptors on lung parenchyma contributes to PCP-related immunopathology by recruiting immune cells that damage lung parenchima. Because PCP was still active when the patient underwent CBT, inflammatory cells derived from the abundant dose of cord blood cells might have localized to the lungs, resulting in fatal IPS. The present case suggests that patients with Artemis deficiency patients with Artemis deficiency should be diagnosed with SCID before having infections, and in cases of PCP they may benefit from HSCT after resolution of PCP with an adequate dose of graft cells, reduced intensity conditioning therapy not including irradiation and sufficient GVHD prophylaxis such as a combination of short-MTX and tacrolimus in an alternative donor setting.