Comparative study of two protocols for quantitative image-analysis of serotonin transporter clustering in lymphocytes, a putative biomarker of therapeutic efficacy in major depression

• Published in: Biomarker research Vol. 5; no. 1; pp. 27 - 8
• Main Authors: Romay-Tallon, Raquel, Rivera-Baltanas, Tania, Allen, Josh, Olivares, Jose M., Kalynchuk, Lisa E., Caruncho, Hector J.
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 22.09.2017; BioMed Central; BMC
• Subjects: Antibodies; Biomarkers; Blood smears; Care and treatment; Committees; Data processing; Depression; Depression (Mood disorder); Development and progression; Ethics; Experiments; Genetic aspects; Health aspects; Image processing; Innovations; Lipids; Lymphocytes; Membrane protein clustering; Membrane proteins; Mental depression; Methodology; Molecular diagnostic techniques; Physiology; Proteins; Psychological aspects; Serotonin; Serotonin transporter; Transport proteins; Biomarkers; Blood smears; Depression; Serotonin transporter; Membrane protein clustering; Lymphocytes
• DOI: 10.1186/s40364-017-0107-6
• ISSN: 2050-7771

The pattern of serotonin transporter clustering on the plasma membrane of lymphocytes extracted from human whole blood samples has been identified as a putative biomarker of therapeutic efficacy in major depression. Here we evaluated the possibility of performing a similar analysis using blood smears obtained from rats, and from control human subjects and depression patients. We hypothesized that we could optimize a protocol to make the analysis of serotonin protein clustering in blood smears comparable to the analysis of serotonin protein clustering using isolated lymphocytes. Our data indicate that blood smears require a longer fixation time and longer times of incubation with primary and secondary antibodies. In addition, one needs to optimize the image analysis settings for the analysis of smears. When these steps are followed, the quantitative analysis of both the number and size of serotonin transporter clusters on the plasma membrane of lymphocytes is similar using both blood smears and isolated lymphocytes. The development of this novel protocol will greatly facilitate the collection of appropriate samples by eliminating the necessity and cost of specialized personnel for drawing blood samples, and by being a less invasive procedure. Therefore, this protocol will help us advance the validation of membrane protein clustering in lymphocytes as a biomarker of therapeutic efficacy in major depression, and bring it closer to its clinical application.