LPS is an immunostimulatory component of Gram-negative bacteria. Acting on the immune system in a systemic fashion, LPS exposes the body to the hazard of septic shock. In this study we report that cysteine-rich secretory protein LCCL domain containing 2 (CRISPLD2/Crispld2; human and mouse/rat versions, respectively), expressed by multitissues and leukocytes, is a novel LPS-binding protein. As a serum protein, median CRISPLD2 concentrations in health volunteers and umbilical cord blood samples are 607 μg/ml and 290 μg/ml, respectively. Human peripheral blood granulocytes and mononuclear cells including monocytes, NK cells, and T cells spontaneously release CRISPLD2 (range, 0.2–0.9 μg/ml) and enhance CRISPLD2 secretion (range, 1.5–4.2 μg/ml) in response to stimulation of both LPS and humanized anti-human TLR4-IgA Ab in vitro. CRISPLD2 exhibits significant LPS binding affinity similar to that of soluble CD14, prevents LPS binding to target cells, reduces LPS-induced TNF-α and IL-6 production, and protects mice against endotoxin shock. In in vivo experiments, serum Crispld2 concentrations increased in response to a nontoxic dose of LPS and correlated negatively with LPS lethality, suggesting that CRISPLD2 serum concentrations not only are indicators of the degree of a body’s exposure to LPS but also reflect an individual’s LPS sensitivity.

Exosomes present in human plasma contain immunity-associated molecules and can induce CD4+ T-cell apoptosis in vitro. Plasma exosomes have the capacity to influence immune responses.

The results suggest that donor iNKT cells could alleviate GVHD symptoms and prolong survival after MHC-mismatched allogeneic BMT, which may be associated with the maintenance in IL-4 levels. These findings indicate that the therapy based on iNKT cells from MHC-mismatched donors has great potential in protection against GVHD after allogeneic hematopoietic stem cell transplantation.

Summary In this study, we expanded regulatory T cells (Tregs) ex vivo from CD4+ CD25+ T cells from cord blood (CB) and CD4+ CD25+ CD127− T cells from adult peripheral blood (APB) and compared the suppressive functions of the newly generated Tregs. The Tregs from CB and APB were expanded either in two cycles with a polyclonal stimulus or in two cycles with an alloantigen stimulus in the first cycle and a polyclonal stimulus in the second cycle. Cell yield after Treg expansion with polyclonal stimulation was greater than that of Tregs expanded with combined alloantigen and polyclonal stimulation. The expanded Tregs expressed high levels of Foxp3, CD39 and cytotoxic T‐lymphocyte antigen‐4 and low levels of CD127, interleukin‐2 and interferon‐γ. After two cycles of expansion, the CB Tregs maintained expression of the GARP gene and showed greater suppressive function than APB Tregs. The CB Tregs that were expanded with two cycles of polyclonal stimulation suppressed not only the polyclonal antigen‐driven responder T (Tresp) cell proliferation but also the HLA mismatched dendritic cell‐driven Tresp cell proliferation. When CB and APB Tregs were expanded with a primary alloantigen stimulus followed by a secondary polyclonal stimulus, the Tregs showed a potent, antigen‐specific suppressive capacity. The Tregs expanded with two cycles of polyclonal stimulation from both CB and APB alleviated acute graft‐versus‐host disease symptoms and prolonged survival in a murine model of graft‐versus‐host disease. In conclusion, CB Tregs expanded with two cycles of polyclonal stimulation had a stronger immunosuppressive function than APB Tregs. It is feasible to obtain human functional alloantigen‐specific Tregs expanded ex vivo from CB and APB in large numbers.

The platelet-derived microparticles, which carried the sCD40L, accumulated in the apheresis platelet concentrates during the 5 days of storage. They primed the fMLP-activated PMN respiration burst, which might be relative to TRALI.