Hey there,
We want to investigate the effects of an anti-neuronal antibody on brain development. Therefore, we inject human antibodies into pregnant dams i.p. and are then interested in the development of the pups.
The neg control ab has been shown to be unreactive against dsDNA, ssDNA, Insulin, LPS and ANA.
In my first experiments, I tried to get an idea of the kinetics of the antibodies after injection (see file attached) by ELISA method. I am a bit confused with these results. If the anti-neuronal ab binds against its antigen, there should be a gradient. I would have expected that AB concentration of the specific ab would be low in pups and dams as there is gradient/immunprecipitation and higher in CTL ab pups as there is no antigen. But AB concentration is higher in dams injected with specific ab... Both ab are of the same subclass and are expected to have simaliar abilities to cross the placenta.
Do you agree with my hypothesis? Or do I miss something? Is the negative control maybe reactive?
I am looking forward to your answers!
Even if your Ab cross the placenta, how you can be sure that your Ab will cross hematoencephalic barrier in the fetus ? Usually, any Ab has MW ~ 150-160 K, and there fore can not cross that barrier. Please see the link below:
https://en.wikipedia.org/wiki/Blood–brain_barrier
I agree with Dr Butnev. Betty, you may want to go through following publication.
http://www.nature.com/news/alzheimer-s-drug-sneaks-through-blood-brain-barrier-1.16291
Thank you very much for your answers!
Honestly, I am bit confused about IgG and blood-brain-barrier function now.
As far as I remember, the neonatal FcReceptor, which is also expressed in the brain, is reversed after birth and participating in the efflux of IgG (e.g. see the link above about AD drug development). But before, it is the other way round. But I do not find any papers that proof that. Did I mix something up?
And then, there is an increasing number of works that show effects of maternal antibodies on fetal brain development.
For example, the work of Singer, Dalton and Braunschweig, which investigate the effect of maternal antibodies of mothers with autistic children. They could all show behavioral abnormalties in the offspring, when pregnant dams got injected with IgG form theses mothers in comparison to controls. Reaction against fetal brain antigens of a size of 37 and 73 kDa were a typical feature of these sera.
In the work of Braunschweig et al., they could show the presence of hum IgG in fetal brains via Western Blot after one single i.v. injection of low-dose maternal antibodies. But as these samples are not PBS-perfused, it is not a proof of the presence of ab's in the parenchyma.
Work from Singer showed IgG present in the brain, identified by immunhistochemistry (see picture).
Also in the model of systemic lupus erythematosus, Lee and colleagues could show that anti-ANA-AB had effects on neurodevelopment on the fetuses.
What do you think about that? I find these experiments quite convincing that maternal IgG enters the fetal brain. How could these effects be explained otherwise?
Thank you very much for your answers in advance!
List of publications:
Singer et al. 2008
Braunschweig et al. 2012
Lee et al. 2009
http://www.sciencedirect.com/science/article/pii/S0165572809001052
http://www.sciencedirect.com/science/article/pii/S0165572812002469
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2615794/
First, a disclaimer: my knowledge comes from infectious diseases, so I am not that familiar with neuronal Ab interactions beyond knowing that Abs are believed to not cross the blood-brain barrier in adults. However, I do not know about pre-natal blood-brain barrier function.
It sounds like you do not know the specificity of the control antibody. It looks like the control antibody could be adsorbed out by binding something in the dams. Since the specific Ab is reactive with a neuronal antigen, it would not be adsorbed out due to sequestration by the blood-brain barrier. Alternatively, could the half-life of the human control Ab simply be shorter in mice than the specific Ab?
I noticed that the concentration of the control antibody appears higher in the pups than the dams. This is not unexpected, as IgG is actively transported across the placenta (for sure in humans and I think also in mice). However, the concentration of specific antibody appears lower in the pups than the dams, though this all could be due to statistical variation.
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