Improved panels for clinical immune phenotyping: Utilization of the violet laser.

BACKGROUND: Clinical diagnostic laboratories are subject to numerous regulations imposed by government agencies. Laboratory developed tests for flow cytometry panels are essentially restricted to the use of analyte-specific reagents (ASR) antibodies. With the advances in clinical flow cytometry systems, there is a trend toward the utilization of blue/red/violet laser flow systems and 8 to 10-color panels. Currently, the selection of commercially available ASR antibodies for the violet laser is very limited. The market is dominated by Brilliant Violet 421 (BV421) manufactured by BD Biosciences and Pacific Blue (PB) manufactured by Beckman Coulter. In this study, we compare BV421 and PB conjugated ASR antibodies. METHODS: Whole blood was stained and acquired on a Gallios flow cytometer system. For single color staining, the stain index (SI) was calculated. For the two panels, the compensation matrix was calculated and the performance of the antibody cocktails analyzed in FCS Express. RESULTS: The results show that five out of six tested BV421 conjugated antibodies have significantly higher SI than their PB counterparts. Furthermore, BV421 antibodies require less compensation for spillover than PB. Finally, BV421 conjugated antibodies give better separation between negative and positive populations in the context of an 8 and 10 color panel without affecting the intensity of the other dyes. CONCLUSIONS: Overall, using BV421 conjugated antibodies results in better separation between populations compared to PB conjugated antibodies without negatively affecting other fluorochromes in our panels. We conclude that the BV421 conjugated ASR antibodies are currently the better available option for clinical flow panels. © 2017 International Clinical Cytometry Society.

Time of Initiating Enzyme Replacement Therapy Affects Immune Abnormalities and Disease Severity in Patients with Gaucher Disease.

Gaucher disease (GD) patients often present with abnormalities in immune response that may be the result of alterations in cellular and/or humoral immunity. However, how the treatment and clinical features of patients impact the perturbation of their immunological status remains unclear. To address this, we assessed the immune profile of 26 GD patients who were part of an enzyme replacement therapy (ERT) study. Patients were evaluated clinically for onset of GD symptoms, duration of therapy and validated outcome measures for ERT. According to DS3 disease severity scoring system criteria, they were assigned to have mild, moderate or severe GD. Flow cytometry based immunophenotyping was performed to analyze subsets of T, B, NK, NKT and dendritic cells. GD patients showed multiple types of immune abnormalities associated to T and B lymphocytes with respect to their subpopulations as well as memory and activation markers. Skewing of CD4 and CD8 T cell numbers resulting in lower CD4/CD8 ratio and an increase in overall T cell activation were observed. A decrease in the overall B cells and an increase in NK and NKT cells were noted in the GD patients compared to controls. These immune alterations do not correlate with GD clinical type or level of biomarkers. However, subjects with persistent immune alterations, especially in B cells and DCs correlate with longer delay in initiation of ERT (ΔTX). Thus, while ERT may reverse some of these immune abnormalities, the immune cell alterations become persistent if therapy is further delayed. These findings have important implications in understanding the immune disruptions before and after treatment of GD patients.

Unique abnormalities of CD4(+) and CD8(+) central memory cells associated with chronic graft-versus-host disease improve after extracorporeal photopheresis.

Chronic graft-versus-host disease (cGVHD) remains a problematic complication of allogeneic hematopoietic stem cell transplantation. Laboratory parameters correlated with cGVHD have not been fully defined, although changes in CD4/CD8 ratios occur and a decrease in CD4(+) central memory T cells has been noted. Extracorporeal photopheresis (ECP) is an effective therapy for steroid-refractory cGVHD. We have noted changes in lymphocyte subsets after ECP. CD4(+) and CD8(+) T-cell central and effector memory populations were enumerated by flow cytometry in a cohort of 37 patients postallogeneic transplantation with symptomatic cGVHD. Of the patients with symptomatic cGVHD, 7 were treated with ECP over 6 months and prospectively assessed for changes in lymphocyte subsets. There was a highly significant correlation of an increase in CD8(+) central memory cells and a concomitant decrease in CD4(+) central memory cells in patients with symptomatic cGVHD. These changes were not detected in patients without cGVHD posttransplantation. In all, 7 patients with cGVHD followed up prospectively during ECP treatment showed a statistically significant normalization of the pattern of CD4(+) and a trend toward normalization of CD8(+) central memory T cells coincident with improvement of cGVHD. These data indicate a high correlation between disturbances in the balance of central and effector memory populations and cGVHD suggesting use in following up responses to therapy. The normalization of central and effector memory populations in response to ECP coincident with clinical improvement of cGVHD support a correlation between these laboratory parameters and cGVHD. Further studies are needed to demonstrate whether laboratory measurements of the magnitude of changes in central and effector memory populations are useful prognostically or can be used to guide response to therapy. The contrasting change in central memory cells (CD8(+) increased versus CD4(+) decreased) in cGVHD provide support for recent reports suggesting unique differences in the differentiation pathways for CD8(+) versus CD4(+) T cells.