Uhl, Cindy B.

Abstract Background Platelet dense granule (DG) deficiencies, including Hermansky-Pudlak syndrome, are relatively common and frequently under-diagnosed hereditary platelet hypofunctional disorders. Among various laboratory tests, platelet whole mount (WM) transmission electron microscopy (TEM) is considered the gold standard method for diagnosing DG deficiencies. Nevertheless, platelet DG TEM testing is still largely a research tool and has not been thoroughly validated and standardized as a clinical test. Furthermore, reference ranges (RR) of DG count/platelet (DGC) have not been adequately established. Aim Our goals were to validate and standardize platelet WM TEM testing and establish reference ranges for platelet DGC. Methods Based on previously established methods (Blood, 33:598-606), we first optimized and standardized various pre-analytical, analytical and post-analytical procedures including sample matrix, sample stability, platelet-rich plasma (PRP) preparation, platelet mounting procedure and DG counting criteria. Then whole blood samples in ACD-B tubes were collected from a total of 128 healthy donors (64 males and 64 females). Platelet DGC, percentage of platelets without any DG (empty platelets), platelet count (PC), mean platelet volume (MPV) and immature platelet fraction (IPF) were measured. In addition, platelet aggregometry analyses were performed on citrated PRP samples from the same donors. Standard statistical analyses were employed in this study. Results DGC and platelet ultra-structure were stable when whole blood samples were stored at room temperature (RT) for up to 4 days. Reproducible DGC and adequate preservation of platelet ultrastructure depended on an optimized mounting method. The DG counting criteria were developed based on previous publications and guidance from Dr. James G. White. Using the same WM TEM images and DG counting criteria, agreements among different technologists (n=5) improved from 60% to 95%. Finally, DGC reference range study using 128 healthy donor samples (age range 18, 72 years) and scoring 100-200 platelets from each donor showed that the DGC distribution of each donor sample was left-skewed with a median of 15% of empty platelets (range: 3, 40). The median DGC was 2.6 with a range of 1.0—5.1. Reference ranges established at the lower 95th percentile for DGC empty platelets is ≤ 31% (95% CI 28, 34) and for the mid-95th percentiles of DGCs between 1.5 and 4.0. DGCs were weakly associated with MPV and IPF (ρ between 0.22 and 0.28); and inversely associated with the percentage of empty platelets (ρ between -0.26 and -0.25). DGC showed no significant association with PC, platelet maximum aggregation or primary slope of aggregation, nor age or gender. Conclusion We validated platelet WM TEM procedures and for the first time established an adult reference range for platelet DGC. The results of association analyses implied that immature platelets may have slightly more DGs. Disclosures: No relevant conflicts of interest to declare.

Abstract The peripheral blood absolute lymphocyte count (ALC) on day 15 after autologous stem cell transplantation (ASCT) has been shown to be an independent predictor for overall survival (OS) for many malignancies including acute myelogenous leukemia (AML), breast cancer, multiple myeloma (MM), primary systemic amyloidosis, and Hodgkin’s and non-Hodgkin’s lymphoma (NHL). However, due to the retrospective nature of previous studies, the peripheral blood lymphocyte subpopulations that predict survival are unknown. To prospectively correlate peripheral blood lymphocyte subpopulations after ASCT and progression free survival, peripheral blood lymphocytes collected from patients before and on day 15 after ASCT were analyzed by four color flow cytometry for CD3, CD4, CD8, CD16, CD 19, and CD56. Patients were then dichotomized into two groups: patients achieving normal numbers of lymphocyte subset (i.e. CD4, CD8, CD19, CD16/56) count versus those who did not. Progression free survival was then analyzed by the Kaplan-Mier method. In our cohort of 14 patients, 9 were male and 5 were female. Nine patients were diagnosed with diffuse large cell B cell lymphoma, two with mantle cell, two with follicular, and one with peripheral T cell lymphoma. On presentation, one patient had stage I, four patients had stage II, four had stage III, and five patients had stage IV disease. The median age at ASCT was 53 years (range: 26–70). The preliminary data from this ongoing prospective study of 14 patients shows that on day 15 after ASCT, 4/14 (29%) of patients achieved a normal CD3 count (median 321, range: 69–2069 cells/ml) 3/14 (21%) achieved a normal CD4 count (median 206, range: 31–1091 cells/ml), 6/14 (43%) achieved a normal CD 8 count (median 88.5, range: 13–813 cells/ml) 1/14 (7%) achieved a normal CD19 count (median 2, range:0–227 cells/ml), and 8/14 (57%) achieved a normal CD16/56 count (median 85.5, range: 10–744 cells/ml). The median follow-up was 12 months (range: 3–45 months). On univariate analysis, patients achieving an absolute NK cell count of ≥ 80 cells/μ on day 15 had significantly improved progression free survival compared to those who did not (not reached vs 3 months, p<0.006, respectively). Similar analysis evaluating the absolute CD3, CD4, CD8, and CD 19 count was not significant (p=0.1, p=0.258, p= 0.06, and p=0.55, respectively). To our knowledge, this is the first report detailing the critical role of NK cell immune reconstitution after ASCT in progression free survival. Figure Figure

Background Lidocaine, a local anesthetic, can be neurotoxic. However, the cellular mechanisms of its neurotoxicity at concentrations encountered during spinal anesthesia remain unclear. Methods The authors examined the mechanisms of lidocaine neurotoxicity in the ND7 cell line derived from rat dorsal root ganglion. Individual neurons were assayed by flow cytometry or microscopy using fluorescent probes of plasma membrane integrity, mitochondrial membrane potential, caspase activity, phospholipid membrane asymmetry, and mitochondrial cytochrome c release. Results In the ND7 cell line, lidocaine at 185 mm x 10 min to 2.3 mm x 24 h caused necrosis or late apoptosis. Equimolar Tris buffer and equipotent tetrodotoxin controls were not toxic, indicating that neither osmotic nor Na-blocking effects explain lidocaine neurotoxicity. The earliest manifestation of lidocaine neurotoxicity was complete loss of mitochondrial membrane potential within 5 min after exposure to lidocaine at a concentration of 19 mm or greater. Consistent with these data, 37 mm lidocaine (1%) induced release of mitochondrial cytochrome c into the cytoplasm, as well as plasma membrane blebbing, loss of phosphatidylserine membrane asymmetry, and caspase activation, with release of mitochondrial cytochrome c to the cytoplasm within 2 h. Treatment with z-VAD-fmk, a specific inhibitor of caspases, prevented caspase activation and delayed but did not prevent neuronal death, but did not inhibit the other indicators of apoptosis. Conclusions Collectively, these data indicate that lidocaine neurotoxicity involves mitochondrial dysfunction with activation of apoptotic pathways.