Effect of Elapsed Time after Blood Collection on the Viability and Mitotic Index of Human Lymphocytes during Karyotype Analysis

Background: Chromosome staining using G banding is a commonly used technique during karyotyping, however, a limited number of laboratories carries out the test. Blood samples must be sent to the laboratory on the same day of sample collection.

Aim: To assess the effect of time passed from sample withdrawal to the beginning of lymphocyte culture on lymphocyte viability and the mitotic index of chromosomal spread.

Methods: Collected peripheral venous blood samples were either processed for chromosome analysis within 2h of samples collection or stored at 4°C then processed at 24h and 48h. Lymphocytes viability was determined by trypan blue and mitotic cells were visualized by the lighted microscope at the 40x objective lens. Mitotic index was calculated per 1000 cell count.

Results: Delay in sample processing more than 24h have a deleterious effect on lymphocyte viability with a significant reduction in mitotic index relative to the freshly processed sample.

Conclusion: Culturing of cells within 24h of sample collection is highly recommended whenever possible and delay more than 48h should be avoided.