Antibody Titer Variance Due to Freezing of Patient Specimens

Jennifer Leigh Rivers, Julianna Jones


In clinical and research laboratories, it is often necessary to analyze stored, frozen serum or plasma specimens, on multiple occasions, over extended periods of time. Although this is common practice, data is limited regarding effects of multiple freeze-thaw cycles on antibody integrity.2 Freeze-thawing combines several protein stress factors, which can induce partial unfolding and subsequent aggregation. Here, we investigated the effects of 12 freeze/thaw cycles on 4 antibodies within the IgG class: Anti-Jka, Anti-Fya, Anti-E, and Anti-c. To perform titrations, serial dilution tubes were set up ranging from 1 to 512. Titrations were performed after 37°C incubation, the titer was documented, and titer scores were calculated. Across 12 freeze/thaw cycles, the Anti Jka and Anti-c titers and scores declined, the Anti-E titer and score declined but varied greatly in the run, and the Anti-Fya titer and score varied throughout. Chi Square testing showed no significant variation in any of the antibody titers or scores. Spearman Correlation analysis returned negative correlation on all tests, insignificant results on Anti-Jka, Anti-Fya, and Anti-E titer and score correlations, and significant results on Anti-c titer and score correlations. Further study is needed to appropriately interpret these findings for applicability and utility in clinical antibody evaluation.


Antibody Titer; Serial Dilution; Freeze/Thaw Cycling; Chi Square Test; Spearman Correlation

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