Pediatric thromboembolism: a national survey in Japan.

Thromboembolism is being detected at increasing rates in pediatric tertiary care hospitals. The incidence of pediatric thrombophilia differs across countries, and is unknown in Japan. We sent a survey to 520 pediatric department heads and 629 specialists, requesting details on patients who developed symptomatic thromboembolism between 2006 and 2010. Of 280 eligible cases, congenital thrombophilia and other conditions were reported. Congenital thrombophilia (n = 54, 19.3 %) comprised defects in protein C (27), protein S (9), and antithrombin (7). None had mutations in factor V Leiden or prothrombin G20210A, both of which are frequent in Caucasians. Non-congenital causes of thrombophilia included congenital heart disease, the use of central venous catheters, nephrotic syndrome, antiphospholipid syndrome, and malignancy with or without use of L-asparaginase. Patients with congenital thrombophilia developed thromboembolism at a significantly younger age (median 1.0 vs. 5.0 years, p = 0.014), had a higher frequency of consanguinity (35.2 vs. 1.8 %, p < 0.001) and post-thrombotic syndromes (29.6 vs. 13.3 %, p = 0.007) than those who did not. Thromboembolism in children with congenital thrombophilia recurred more frequently (50.0 vs. 13.7 %, p < 0.001) and was associated with more sequelae (61.1 vs. 37.2 %, p = 0.009) than in children without congenital thrombophilia. This nationwide survey provides the first comprehensive study of Japanese children with symptomatic thromboembolism. Significant recurrence and sequelae require optimized standards.

Clinical significance of CD70 expression on T cells in human T-lymphotropic virus type-1 carriers and adult T cell leukemia/ lymphoma patients.

Human T-lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia/lymphoma (ATL). Miscellaneous host immune surveillance systems control T-cell growth/leukemogenesis during HTLV-1 infection. We characterized CD70 and CD27 expression on lymphocytes of HTLV-1 carriers and patients with ATL (study approved by the local Medical Ethical Committee). High CD70 expression was observed on CD4 + CD25+ T cells from patients with acute-type ATL, while patients with smoldering- or chronic-type ATL and HTLV-1 carriers exhibited lower expression. Furthermore, significantly higher CD27 expression was observed on HTLV-1-specific CTLs. We found an association between CD70 expression on CD4 + T cells and HTLV-1 infection; increased CD70 expression was observed after exposure to Tax. Moreover, addition of anti-CD70 antibodies enhanced the CD107a surface mobilization of HTLV-1 Tax-specific CTLs following Tax-peptide stimulation in the PBMCs of carriers. These data demonstrate the important role of the CD70/CD27 axis in immune responses in HTLV-1 carriers and ATL patients.

HTLV-1 specific CD8+ T cell function augmented by blockade of 2B4/CD48 interaction in HTLV-1 infection.

CD8+ T cell response is important in the response to viral infections; this response though is regulated by inhibitory receptors. Expression of inhibitory receptors has been positively correlated with CD8+ T cell exhaustion; the consequent effect of simultaneous blockade of these inhibitory receptors on CD8+ T cell response in viral infections have been studied, however, the role of individual blockade of receptor-ligand pair is unclear. 2B4/CD48 interaction is involved in CD8+T cell regulation, its signal transducer SAP (signaling lymphocyte activation molecule (SLAM)-associated protein) is required for stimulatory function of 2B4/CD244 on lymphocytes hence, we analyzed 2B4/CD244 (natural killer cell receptor) and SAP (signaling lymphocyte activation molecule(SLAM)-associated protein) on total CD8+ and HTLV-1 specific CD8+T cells in HTLV-1 infection and the effect of blockade of interaction with ligand CD48 on HTLV-1 specific CD8+ T cell function. We observed a high expression of 2B4/CD244 on CD8+ T cells relative to uninfected and further upregulation on HTLV-1 specific CD8+ T cells. 2B4+ CD8+ T cells exhibited more of an effector and terminally differentiated memory phenotype. Blockade of 2B4/CD48 interaction resulted in improvement in function via perforin expression and degranulation as measured by CD107a surface mobilization on HTLV-1 specific CD8+ T cells. In the light of these findings, we thus propose an inhibitory role for 2B4/CD48 interaction on CD8+T cell function.