Caudata.org: Newts and Salamanders Portal

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
Did you know that registered users see fewer ads? Register today!

Axolotl Immune System

Kal El

New member
Joined
Nov 13, 2007
Messages
426
Reaction score
23
Location
Brisbane
G'day, everyone,

I was just wondering if any one knows whether an axolotl has the ability to develop an acquired immunity to certain pathogens (i.e. the adaptive immune system)?

To me, the mucus that envelops the axolotl is some what analogous to the innate immune system in that it protects the axolotl from invading pathogens without much specificity (or perhaps there is some, i.e. PAMPs?)

Regarding the adaptive immune system, some fish have the ability to develop immunity (to some degree) to Ich when sensitised in previous cases. So, is it possible for an axolotl to develop similar mechanisms of immunity to Ich or other pathogens?

Jay.
 

Darkmaverick

Site Contributor
Joined
Mar 11, 2008
Messages
2,032
Reaction score
82
Location
Sydney
Hi there,

Sorry im no expert on axolotl physiology or medicine, but i believe axolotls too have the same basic immune system - Innate and acquired, and within acquired immunity, both cell mediated and humoral immunity. I think as with the immunology of most species, an inidividual axolotl's immune system to a foreign 'epitope' be it microbial or otherwise, is rather multi-factorial.

I have tried researching for axolotl medicine from my vet faculty library as well as some online search databases like medline and pubmed, however, sad to say literature on axolotl medicine is really extremely rare. I can however draw inferences from some of the observation/anecdotes reported by other enthusiasts such as how Wildtypes are more hardy or how certain in-bred lines are more susceptible to disease to substantiate that there is variability in acquired (adaptive) immunity. As most of us (especially breeders) would know hybrid vigour can confer resistance in stock.

I do agree that the slime coat layer have an immunological role (probably innate non specific) since the skin is the first line of defense against pathogens. Axolotls do have leukocytes (probably similar to neutrophils/lymphocytes/macrophages/eosinophils/basophils) that have a dynamic and inter-related role in their acquired immunity. I have heard of stories of how some owners have reported that a particular axolotl appears more susceptible to lets say fungus even though that axolotl is housed in the same tank as other axolotls and receive the same food etc. I think this reinforces the idea that they do have varying degrees of acquired immunity.

The only way to accurately assess this is probably some further scientific research such as analysing the blood of axolotls and assess cytokine activity (ie interferon gamma) of white cells via mitogenic stimulation/flow cytometry. However this can only be done in research/academic facilities through strict ethical code of course.

Just my 2 cents. (Sorry even though i am a small animal vet, im not trained in exotics)

Regards
 

oceanblue

New member
Joined
Sep 27, 2007
Messages
654
Reaction score
52
Location
Brecon beacons
Axolotls demonstrate an immune response to antigens, but do not appear to show the increase in response of mammals to repeated booster injections. I found this article available via pub med as a pdf:

Thymus independent anti-horse erythrocyte antibody response and suppressor T cells in the Mexican axolotl (Amphibia, Urodela, ambystoma mexicanum).
J Charlemagne Immunology. 1979 April; 36(4): 643–648.

It describes how their immune system may respond to bacteria and other pathogens: They develop a slow rising antibody response after a single exposure.
 

Darkmaverick

Site Contributor
Joined
Mar 11, 2008
Messages
2,032
Reaction score
82
Location
Sydney
This article is most interesting. It suggests that axolotls do have an acquired immune response (humoral response of antibody production upon antigenic stimulation), however it does not have the more 'evolved' memory cell function of other mammalian species. Furthermore, the rise in antibody titre is comparatively slow though gradual. What would be interesting to see if there is differentiation of the antibody types - primary IgM or secondarily mounted IgG/ secretory IGA etc. If there are rising titres of IgG for eg, that further lends weight that they do have an adaptive immunity. They do not appear to have the plasma cell equivalent of a B cell previously primed by the memory of an antigenic exposure.

THe mention of T cell suppressor funtion really reinforces the notion that cell-mediated immunity may play a role.

Thank you for the interesting article. I should have widen my search period way back!!

Cheers
 

Kal El

New member
Joined
Nov 13, 2007
Messages
426
Reaction score
23
Location
Brisbane
I had completely forgotten about this thread until just now because I was bored and was randomly searching.

Thanks to both Darkmaverick and Oceanblue for sharing their thoughts. Oceanblue, the article was a very good read.

I can't really speculate on the immune system of an axolotl (hence, the thread), but as the article says, axolotls appear to be thymus independent when it comes to T-B cell collaboration, in particular the activation of the naive B cell. But, it also mentions that it can't rule out the possibility that exposure to other epitopes may elicit a thymus dependent response, in which case, you would expect a switch in Ig class.

The study of cytokines would also be interesting, especially IL-2, IL-12, and IFNy, as these promote cellular immunity from a naive CD4 T cell.

Although, I didn't understand the article too well, this excerpt made me think:

"In this case, a helper T-cell subset in the axolotl remains theoretically possible. Another hypothesis could be that the axolotl definitely lacks helper T cells. It is not actually possible to justify one or other of these hypotheses in regard to our actual results. Nevertheless, several arguments argue for the lack of some T-cell subsets in urodele."

Perhaps a study investigating whether the inhibiting CTLA-4 co-stimulatory signal is pertinent in CD4 T cells, can offer some answers. Thoughts?

Thanks, again.

Jay.​
 

Darkmaverick

Site Contributor
Joined
Mar 11, 2008
Messages
2,032
Reaction score
82
Location
Sydney
Hi all,

What struck me as most unusual was that it appears about 15 years back there was this flurry of research activity on axolotls and then suddenly things just died down abruptly. Most axolotl research papers are from years back or maybe there might still be research going on but much more low key now.

Perhaps it might be much more challenging obtaining axolotl blood samples than it appears. Because of their relatively small size (opposed to lets say a cat), their circulating blood volume is also much less. Proportionately, we can only ethically obtain only a small amount of blood at a time. And obviously blood samples are most essential for the study of immune function.

Nontheless, if i were to design an experiment to study immune function in axolotls using modern equipment, what i would do is first ascertain statistically how many subjects i require. Thereafter, i would obtain a sample of blood which i would i perhaps use ficoll separation technique to obtain the buffy coat (just the leukocytes). I would then mitogenically stimulate different buffy coat aliquots with different antigenic stimulus (mitogens) such as saprolegnia extract, extract from aeromonas hydrophila, columnaris, pseudomonas and if possible even from anchorworm or lets say common viruses. Different pathogens will preferentially affect different cell types in the buffy coat.

Thereafter, i would aim to use different antibodies tagged with a flurochrome (different coloured glowy indicators for each) specifically to identify CD4 versus CD8 T lymphocytes. I could then also try to permeabilise the cells to perform intracellular staining of cytokines such as interferon gamma, interleukin 2 and 12 as Kal El correctly suggested. By using a flow cytometry apparatus, we can then identify the population of lymphocytes based on the scatter pattern. The presence of the antibody tagged flurochromes will then further allow an evaluation of unstimulated versus mitogenically stimulated samples to make a compare and contrast study showing which population of lymphocytes are activated with a particular antigenic stimulus. It also allows us to quantify the magnitude of cytokine production which can allow us to see if the immune response leans towards a cell mediated pathway.

Further evaluations can be made to also concurrently study the humoral response by means of measuring the antibody titires from these blood samples. Perhaps using indirect immunofluorescene assay/ ELISA and even immunohistochemistry.

Of course, i made everything sound so much easier than it seems. It would be really hard to obtain THAT much blood samples and also it would be hard to obtain antibodies that are specific enough not to create too much background 'noise'. Furthermore, i doubt that there are any research papers that has a optimised protocol for flow cytometry analysis or any of the immuno based assays on axolotls if any exist in the first place.

Nontheless, its always good to dream. Perhaps one day it could be done! I think Oceanblue would be the best person to ask if the experiment is feasible. He is our very own in house pathologist !

Cheers
 

oceanblue

New member
Joined
Sep 27, 2007
Messages
654
Reaction score
52
Location
Brecon beacons
Sorry I'm out of my field a bit on the immune system, so I've no sensible suggestions as to how to investigate it.

This article from Biomed central "Transcriptional response of Mexican axolotls to Ambystoma tigrinum virus (ATV) infection BMC Genomics 2008, 9:493" seems to have a lot of information in it and might give some clues to those in the field what is going on! There are people still working on the axolotl immune system.

http://www.biomedcentral.com/1471-2164/9/493
 
Last edited:

Darkmaverick

Site Contributor
Joined
Mar 11, 2008
Messages
2,032
Reaction score
82
Location
Sydney
Hi all,

Oceanblue always manages to find insightful articles! The article link provided a list of references, a lot pertaining to axolotl immune studies.

After reading through the paper, i feel that although that research team used modern analytical tools and methods, the study may not fully give a complete picture. In particular, they used the gene chip microarray technique to study gene expression. My argument is that transcription (gene expression) doesn't always lead on to translation of the proteins such as antibodies and cytokines which a method like cytokine staining and cytometry can reveal. However, that said, gene expression can still be indicative of the immune pathway the axolotl takes upon antigenic stimulus.

I liked how the team used immunohistochemistry to stain samples from the spleen etc. that can tell us where lymphocyte activity is clustered. I also liked how they used real time polymerase chain reaction which can give very accurate gene study. Im glad there are still research going on to understand more about axolotls. Perhaps i should try find funding to conduct a research myself here in sydney.

I would also like to draw attention to this article:


Koniski AD, Cohen N: Reproducible proliferative responses of salamander (Ambystoma mexicanum) lymphocytes cultured with mitogens in serum-free medium. Dev Comp Immunol 1992, 16:441-451.

It actually has some preliminary mitogenic stimulus protocol which can indeed prove most useful!

Cheers
 
General chit-chat
Help Users
  • No one is chatting at the moment.
    There are no messages in the chat. Be the first one to say Hi!
    Top