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Published on: September 16, 2012
Exploring the feasibility of multi-site flow cytometric processing of gut associated lymphoid tissue with centralized
Ian McGowan1, Peter A Anton2, Julie Elliott2
1University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America.
Insights
Standardized protocols for collecting and analyzing intestinal immune cells (MMC) and peripheral blood mononuclear cells (PBMC) can reduce, but not eliminate, data variability in multi-site studies. Centralized processing may offer more robust results.
Area of Science:
- Immunology
- Clinical Trial Methodology
Background:
- Multi-site clinical studies require consistent data collection for reliable results.
- Characterizing immune cell phenotypes, particularly T cells in gut-associated lymphoid tissue (GALT), is crucial for understanding immune responses.
- Flow cytometry is a key technique for immune cell analysis, but inter-site variability can be a challenge.
Purpose of the Study:
- To assess if standardized protocols minimize variability in flow cytometry data for mucosal mononuclear cells (MMC) and peripheral blood mononuclear cells (PBMC) across two study sites.
- To evaluate the effectiveness of centralized analysis in reducing data discrepancies in multi-site immunological studies.
Main Methods:
- Healthy male volunteers provided rectal biopsies for MMC isolation and peripheral blood for PBMC collection at two sites.
- Standardized protocols for tissue processing, cell isolation, and T cell phenotyping by flow cytometry were implemented.
- Quality control involved cryopreserved PBMC (qPBMC) from a single donor, with all data analyzed centrally.
Main Results:
- Overall CD4+ and CD8+ T cell frequencies in qPBMC were equivalent between sites.
- Significant inter-site differences were observed for most T cell activation and memory subsets in qPBMC, PBMC, and MMC.
- Standardized protocols reduced, but did not eliminate, variability in flow data.
Conclusions:
- Centralized processing, flow cytometry, and analysis of samples may yield more robust data in multi-site studies.
- While standardization helps, complete elimination of variability requires careful consideration of centralized vs. site-specific processing, including sample shipping and cryopreservation logistics.
Abstract:
The purpose of this study was to determine whether the development of a standardized approach to the collection of intestinal tissue from healthy volunteers, isolation of gut associated lymphoid tissue mucosal mononuclear cells (MMC), and characterization of mucosal T cell phenotypes by flow cytometry was sufficient to minimize differences in the normative ranges of flow parameters generated at two trial sites. Forty healthy male study participants were enrolled in Pittsburgh and Los Angeles. MMC were isolated from rectal biopsies using the same biopsy acquisition and enzymatic digestion protocols. As an additional comparator, peripheral blood mononuclear cells (PBMC) were collected from the study participants. For quality control, cryopreserved PBMC from a single donor were supplied to both sites from a central repository (qPBMC). Using a jointly optimized standard operating procedure, cells were isolated from tissue and blood and stained with monoclonal antibodies targeted to T cell phenotypic markers. Site-specific flow data were analyzed by an independent center which analyzed all data from both sites. Ranges for frequencies for overall CD4+ and CD8+ T cells, derived from the qPBMC samples, were equivalent at both UCLA and MWRI. However, there were significant differences across sites for the majority of T cell activation and memory subsets in qPBMC as well as PBMC and MMC. Standardized protocols to collect, stain, and analyze MMC and PBMC, including centralized analysis, can reduce but not exclude variability in reporting flow data within multi-site studies. Based on these data, centralized processing, flow cytometry, and analysis of samples may provide more robust data across multi-site studies. Centralized processing requires either shipping of fresh samples or cryopreservation and the decision to perform centralized versus site processing needs to take into account the drawbacks and restrictions associated with each method.
