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Updated: Aug 8, 2026
C. elegans Chemotaxis Assay
Published on: April 27, 2013
Within day and between day variation of the in vitro under agarose chemotaxis assay in bovine
T van Werven1, J van den Broek, E N Noordhuizen-Stassen
1Department of Herd Health and Reproduction, Utrecht University, The Netherlands. tine@bdv.dgk.ruu.nl
Insights
This study analyzed variation in bovine chemotaxis assays. Taking blood samples at the same time daily and using adjusted least squares means improves the stability of chemotactic activity measurements.
Area of Science:
- Veterinary Immunology
- Cellular Immunology
Background:
- Chemotaxis assays are crucial for assessing immune cell function.
- Understanding variation in these assays is key to reliable results.
- Bovine leukocyte chemotaxis presents unique challenges for standardization.
Purpose of the Study:
- To determine within-day and between-day variation in the in vitro under agarose chemotaxis assay for bovine peripheral white blood cells.
- To estimate a more stable immunological parameter for chemotactic activity using experimental data.
- To provide recommendations for optimizing chemotaxis assay protocols in cattle.
Main Methods:
- Experiment I: Collected blood samples from eight cows every 4 hours over 24 hours, replicated on three separate days.
- Experiment II: Monitored 12 cows for 8 consecutive days, collecting blood samples daily at 0730 for chemotaxis assay.
- Statistical analysis involved conditional auto-regression modeling to estimate adjusted least squares means.
Main Results:
- Significant within-day variation in chemotactic differentials was observed.
- Between-day differences in chemotaxis were also significant, showing random day-to-day fluctuations.
- A first-order conditional auto-regression model effectively estimated daily chemotactic values based on the previous day.
Conclusions:
- Standardize blood sampling times to the same time of day to mitigate within-day variation in chemotaxis assays.
- Utilize adjusted least squares means for chemotactic differentials when analyzing sequential data.
- Adjusted means offer a more stable and less randomly variable parameter for assessing bovine chemotactic activity.
Abstract:
The present study was conducted to determine within day variation (experiment I) and between day variation (experiment II) of the in vitro under agarose chemotaxis assay. Further, results from experiment II were used to estimate a more stable immunological parameter for the chemotactic activity. In experiment I, blood samples of eight cows were taken every 4 h starting at 0800 during a 24 h period. This procedure was replicated on three different days with peripheral white blood cells of lactating bovine. Chemotactic differential showed variation within a day. The differences between samplings were not constant over the days, but varied randomly from day to day. In experiment II, 12 cows were followed for 8 consecutive days and blood samples for chemotaxis assay were taken once a day at 0730. Differences between the days were significant. With a conditional auto regression model of the first order adjusted least squares means of each cow were estimated over the 8 consecutive days. The chemotactic value of a day was used to estimate the value of the next day. Expanding the model with more previous days did not improve the model. The results of this study indicate that blood samples for chemotaxis should be taken at the same time of the day to control for within day variation. If a sequence of chemotactic values is available we strongly suggest working with adjusted least square means of chemotactic differentials. These adjusted means show less random variation and are a more stable parameter for chemotactic activity.
