Effect of multiple freeze-thaw cycles on the stability of positive anti-treponemal serum samples

• Main Authors: Marcia Jorge Castejon (Author), Rosemeire Yamashiro (Author), Camila C. Oliveira (Author), Elaine L. Oliveira (Author), Edilene P. R. Silveira (Author), Carmem Aparecida F. Oliveira (Author)
• Format: Book
• Published: Sociedade Brasileira de Patologia Clínica, 2017-08-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1678-4774; 10.5935/1676-2444.20170038
• Keywords: serum; antibodies; Treponema pallidum; quality control; reactivity-stability; Pathology; RB1-214
• Source: Jornal Brasileiro de Patologia e Medicina Laboratorial, Vol 53, Iss 4, Pp 246-251 (2017)

ABSTRACT Introduction: Biological samples have long been used in multiple laboratory investigations, and this procedure has been an issue of concern, as the samples are submitted to repeated freeze-thaw cycles, which may affect the results of a particular immunodiagnostic assay, due to the occurrence of physical damage to the antibody of interest. Objective: This study aimed at investigating the impact of successive freeze-thaw cycles on the stability of serum samples stored at -20ºC regarding the reactivity of anti-treponemal antibodies. Methods: At the Immunology Center-Instituto Adolfo Lutz (IAL), the analyzed serum samples analyzed were prepared and established as reference material for anti-treponemal immunodiagnostic assays. Sera stability was evaluated by chemiluminescence assay in samples submitted to 25 successive freeze-thaw cycles, ranging from 6 to 174 cycles. Results: Neither statistically significant effect on the reactivity of anti-treponemal antibodies (p-value > 0.05), nor adverse effect were observed in weakly reactive samples, such as the occurrence of false-negative results. Conclusion: It was shown that 174 freeze-thaw cycles of anti-treponemal sera did not affect the stability and the quality of samples, when evaluated by chemiluminescence assay.