Improvement of microangiopathy after haematopoietic stem cell transplantation in systemic sclerosis.

OBJECTIVES: Haematopoietic stem cell transplantation (HSCT) is a treatment option for patients with severe systemic sclerosis (SSc), but the efficacy of the procedure in remodelling the nailfold microvascular array is largely unknown. Therefore, this study aimed to evaluate the effect of HSCT on microangiopathy assessed through nailfold capillaroscopy (NC) and to compare the results with findings in patients receiving conventional immunosuppression. METHODS: We included SSc patients with severe SSc and whose pre- and post-treatment NC images were available. Findings in patients treated with HSCT were compared with patients not treated with HSCT. Images were scored by two independent observers blinded for clinical data and treatment history. Capillary pattern was determined and semiquantitative scores from 0 (no changes) to 3 (>66% alterations per millimetre) were used to quantify the degree of specific microvascular characteristics. Changes in severity of microangiopathy between baseline and post-treatment were compared between groups. RESULTS: Images of 18 HSCT patients and 21 controls were scored. From baseline to follow-up, 33% of HSCT patients showed improvement from scleroderma pattern to normal NC, compared to 6% of controls (p=0.15). Pre- to post-treatment differences in semiquantitative scores showed significant improvement in HSCT patients compared to controls regarding capillary loss (-0.5 vs. 0.0, p<0.05) and disorganisation (-0.8 vs. 0.0, p<0.05). CONCLUSIONS: The degree of microangiopathy improved significantly in severe SSc patients treated with HSCT compared with patients receiving conventional immunosuppressive therapy.

T cells expressing the activating NK-cell receptors KIR2DS4, NKG2C and NKG2D are elevated in paroxysmal nocturnal hemoglobinuria and cytotoxic toward hematopoietic progenitor cell lines.

OBJECTIVE: To investigate the presence of T cells with natural killer cell receptors (NKR) in paroxysmal nocturnal hemoglobinuria (PNH), and their potential involvement in clonal expansion of glycosylphosphatidylinositol (GPI)-deficient hematopoietic stem cells by selective immune attack to normal and not GPI-deficient hematopoietic stem cells. MATERIALS AND METHODS: By flow cytometry, the frequency and number of T cells expressing NKR was evaluated in 39 PNH patients and compared to healthy controls. Elevated T cell subsets in PNH were assessed for differential cytotoxic lysis of GPI(+) and GPI(-) CD34(+) hematopoietic progenitor cell lines. RESULTS: In PNH patients, the frequency (p < 0.001) and absolute number of T cells expressing the NKR CD56 (p = 0.01) were significantly increased. Furthermore, a higher percentage of T cells expressed the activating NKR NKG2D (p < 0.01), NKG2C (p < 0.01), and KIR2DS4 (p = 0.01). Further characterization showed that these populations predominantly consist of CD8(+) effector memory CD45RA(+) T cells (T(EMRA)). NKR(+) cytotoxic T-lymphocyte lines isolated from PNH patient peripheral blood and bone marrow displayed high cytotoxicity towards CD34(+) hematopoietic progenitor cell lines and K562 cells, suggesting major histocompatibility complex class I-independent cytotoxicity. These cytotoxic T lymphocyte (CTL) lines are capable of differential lysis of GPI(+) and GPI(-) hematopoietic cell lines, however, not in all cases. This suggests that multiple factors, such as the highly activated status of in vitro cultured CTLs, influence whether GPI-dependent lysis occurs. CONCLUSIONS: The increased frequency of CD8(+) effector-memory T cells with activating NKR and cytotoxicity toward hematopoietic cell lines suggests involvement in bone marrow failure and clonal expansion in PNH.