A question of cytokine kinetics. In an activation assay, we usually want to measure effects of our treatment (whatever this might be) on pro- or anti-inflammatory cytokines. Most commonly researchers pick a time point based on certain criteria and measure the levels of these mediators.
However, absence of evidence doesn't necessarily mean evidence of absence; for example, lack of difference between control and treated groups might derive from measurement at a wrong time point after the mediator reaches its peak and treatment has its optimal effect and after which compensatory mechanisms might fade the effect out.
To circumvent this potential, it is possible to carry out a time course of the kinetics of all mediators measured in the assay and use different time points to measure different marker levels. Alternatively, could one pick a shorter but common time point to measure different mediator levels solely based on knowledge of their half lives? If such a time point was chosen, in theory the levels of all markers would be relevant to the treatment received.
Of course, the argument against such a rationale is whether the drug used would have sufficient time to act, but I want to see how people feel about this approach.
Dear Dr. Kapellos. If your final goal is to get information for the best treatment protocol for patients, I would not appreciate in vitro cytokine measurements data so much. In vivo, especially in patients suffering from autoimmune diseases or intractable inflammatory disorders, stimulation of immune system occur continuously and thus so the production of cytokines. Under those conditions, half lives of cytokines may not be so important. In practical sense, the information we need is the levels of cytokine before and after the treatment. The treatment time is anyway decided by the symptoms of patients, but not by the levels of cytokines.
Sometimes for in vitro and in Vivo assays, a time course is needed in order to study an effect of specific agents on inhibition or activation of cytokine levels. For example, TNF levels, after LPS challenge for example, only go up transiently. So one needs to either know beforehand, what time periods are needed, or determined empirically.
AS Dr. Uede stated, when treating patients, it may not be so important. But in preclinical work, it may be of utmost importance to find conditions where your agent has a measurable effect.
A time course is needed to study the effect of specific agents on the target action here the mediators. Use of common time point to measure different mediators may not yield successful results. Well. if you try, all the best. lalitha kabilan
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