Post-transplant lymphoproliferative disorder (PTLD) is the most after SOT (liver and lungs) and review cases reported in the literature. common treatment related malignancy that occurs after solid organ Both patients had a bimodal response to therapy with initial transplantation (SOT). PTLD has extended from its initial description eradication of bulky nodal disease with regimens typically used to as an Epstein-Barr virus (EBV)-driven B-cell proliferation to include treat leukemia, but persistence of low-level clonal T-cells in marrow, EBV-negative and non B-lineage cases. T-cell PTLD (T-PTLD) is rare CSF and lung in one case. Pediatr Blood Cancer 2008;50:415-in both adults and children. We report two cases of pediatric T-PTLD 418.

BACKGROUND Bone marrow mesenchymal stem cells (BMSCs) are capable of shifting the microglia/macrophages phenotype from M1 to M2, contributing to BMSCs-induced brain repair. However, the regulatory mechanism of BMSCs on microglia/macrophages after ischemic stroke is unclear. Recent evidence suggests that mesencephalic astrocyte–derived neurotrophic factor (MANF) and platelet-derived growth factor-AA (PDGF-AA)/MANF signaling regulate M1/M2 macrophage polarization. AIM To investigate whether and how MANF or PDGF-AA/MANF signaling influences BMSCs-mediated M2 polarization. METHODS We identified the secretion of MANF by BMSCs and developed transgenic BMSCs using a targeting small interfering RNA for knockdown of MANF expression. Using a rat middle cerebral artery occlusion (MCAO) model transplanted by BMSCs and BMSCs–microglia Transwell coculture system, the effect of BMSCs-induced downregulation of MANF expression on the phenotype of microglia/macrophages was tested by Western blot, quantitative reverse transcription-polymerase chain reaction, and immunofluorescence. Additionally, microglia were transfected with mimics of miR-30a*, which influenced expression of X-box binding protein (XBP) 1, a key transcription factor that synergized with activating transcription factor 6 (ATF6) to govern MANF expression. We examined the levels of miR-30a*, ATF6, XBP1, and MANF after PDGF-AA treatment in the activated microglia. RESULTS Inhibition of MANF attenuated BMSCs-induced functional recovery and decreased M2 marker production, but increased M1 marker expression in vivo or in vitro . Furthermore, PDGF-AA treatment decreased miR-30a* expression, had no influence on the levels of ATF6, but enhanced expression of both XBP1 and MANF. CONCLUSION BMSCs-mediated MANF paracrine signaling, in particular the PDGF-AA/miR-30a*/XBP1/MANF pathway, synergistically mediates BMSCs-induced M2 polarization.

Mast cell disease (MCD) is a rare proliferation that may be easily confused with other hematopoietic tumors. Several paraffin section antibodies immunoreact with mast cells but most are not specific. Tryptase, a specific marker of mast cells, may not be cost-effective to maintain in a laboratory because of the rarity of these lesions. This study was undertaken to assess the immunoreactivity of MCD and attempt to select a limited antibody panel for diagnosing MCD among hematopoietic tumors that morphologically mimic MCD. Immunophenotyping of cutaneous ( 10 cases) and extracutaneous (18 cases) MCD, as well as 94 other hematopoietic neoplasms, was performed on paraffin sections. All cases of MCD showed strong and diffuse positivity for CD68 and tryptase. In the vast majority of the cases, the mast cells were also positive for CD117 (27 of 28) and CD43 (25 of 27). Four cases (40%) of cutaneous MCD demonstrated a subpopulation of mast cells expressing myeloperoxidase (MPX), whereas all extracutaneous MCD were negative for MPX. Two (40%) extramedullary myeloid tumors (EMT) expressed CD43, CD68, CD 117, and MPX, but none expressed tryptase. CD43, CD68, CD117, and tryptase were expressed by 25%, 1%, 15%, and 1%, respectively, of all B-cell lymphoid neoplasms, and none expressed more than one of these four antigens. We conclude that (1) cutaneous MCDs may demonstrate a subpopulation of MPX antigen expressing tumor cells and may be confused with cutaneous involvement by myeloid leukemia if other antibodies are not used; (2) tryptase is the most specific mast cell marker among the antibodies studied; and, (3) the detection of tryptase, together with CD68, CD117, and usually CD43, is unique to MCD among hematopoietic tumors.