An early increase of CD56bright natural killer subset as dominant effect and predictor of response to extracorporeal photopheresis for graft-versus-host disease.

BACKGROUND: CD56bright natural killer (NK) regulatory cells were recently shown to display a differential impact on the risk of developing extensive chronic graft-versus-host disease (GVHD). To date no study has definitively established which immune populations are most responsible for the immunomodulatory effects or response to extracorporeal photopheresis (ECP) for GVHD. STUDY DESIGN AND METHODS: To test the role of CD56bright NK cells in ECP, a prospective enhanced flow cytometry follow-up of immune subsets (CD19+, CD3+, CD3+/CD4+, CD3+/CD8+, CD3-/CD56+, CD3-/CD56bright , and CD3-/CD56dim ) was performed in 32 patients with GVHD who underwent 552 procedures. RESULTS: An early increase of CD56bright NK cells was found as a hallmark effect to ECP, particularly during the first 3 months of treatment. This was also supported by the ability to predict for complete responses when this increase was expressed as a higher CD56bright versus CD56dim NK cells ratio. Among the immune subsets tested, the only variable that had direct influence on response to ECP was a CD56bright/dim ratio more than 0.16 (hazard ratio [HR] 4.32, p = 0.014; HR 5.8, p = 0.007, at 2 and 3 months of ECP treatment, respectively). CONCLUSION: These findings argue for exploring strategies for priming a CD56bright NK cell expansion during ECP and providing additional and potentially relevant data for revisiting the underpinning cellular mechanisms of ECP that could generate that expansion.

Quality assessment and transfusion efficacy of buffy coat-derived platelet concentrates washed with platelet additive solution.

BACKGROUND: Transfusion of washed platelet concentrates (W-PC) is recommended for some patients, such as those who have had previous severe allergic transfusion reactions. However, we still lack a standardised method for preparing these products. Here, we assessed the effect of a manual washing procedure on in vitro platelet quality and on the transfusion efficacy of W-PCs. MATERIALS AND METHODS: Buffy coat-derived W-PC in Composol solution were prepared by one-step centrifugation. Platelet activation and function were evaluated before and after washing by means of: (i) CD62 expression by flow cytometry; (ii) platelet aggregation (LTA); and (iii) the VerifyNow® P2Y12 test. A pilot prospective transfusion study was carried out in 11 onco-hematology patients receiving, in a short time, two consecutive transfusions: one with standard PC (S-PC) and one with W-PC. The post-transfusion platelet increment, the 1 h and 24 h corrected count increment (CCI) and occurrence of bleeding events were used as indices of transfusion efficacy. RESULTS: Platelet recovery in W-PC was 84.8±5.4%. Washing slightly increased platelet activation in W-PC vs pre-washed samples (% CD62+ platelets 23.6±7 vs 14.8±1; p=0.03). As compared to prewash samples, platelet reactivity of W-PC as measured by VerifyNow® P2Y12 was significantly lower with ADP (PRU 32.2±37.7 vs 4.2±2.4, p=0.027), but similar using TRAP. Platelet aggregation responses to TRAP, collagen, ristocetin and arachidonic acid were maintained in W-PC. The pilot transfusion trial showed similar 1 h (13.5±5.6 vs 11.5±7.3, p=0.49) and 24 h (11±7.2 vs 9±6.5, p=0.48) CCI for S-PC and W-PC. Transfusion of W-PC was not associated with an increased number of bleeding events. DISCUSSION: We have set up a simple method to obtain buffy-coat-derived W-PC, which has minor effects on in vitro platelet quality and transfusion effectiveness. This procedure can be easily implemented in transfusion centres for on-demand preparation of washed platelets.

Persistent cytotoxic T lymphocyte expansions after allogeneic haematopoietic stem cell transplantation: kinetics, clinical impact and absence of STAT3 mutations.

Peripheral expansion of cytotoxic T lymphocytes (CTL) derived from the graft in the initial stages of allogeneic haematopoietic stem cell transplantation (alloHSCT) immune recovery is a well-known physiological event. The description of symptomatic large granular lymphocyte leukaemia in this setting may generate uncertainty, mostly in those cases in which the CTL expansion (CTLe) persists beyond the early transplantation period. We aimed to assess the nature of CTLe during the post-alloHSCT period in 154 adult patients with a long-term surveillance. We studied the longitudinal kinetics of those expansions, their relationship to clinical events, and their phenotypic and molecular features, including recently reported CTL leukaemia-STAT3 mutations. Persistent relative CTLe cases are frequent (49%), related with thymoglobulin prophylaxis (P ≤ 0·001), acute graft-versus-host disease (GVHD, P = 0·02), and reduced intensity conditioning (P = 0·04). Absolute CTLe are scarce (9%) and related to chronic GVHD. T cell receptor rearrangement was reported as clonal and oligoclonal in the majority of patients with CTLe. The absence of STAT3 mutations and the CD8/CD4 declining longitudinal kinetics in the late period supports its benign nature, expressed clinically by the null detrimental impact of these expansions on post-transplant outcome and/or serious infectious events.