read my post on interleukin-15 much further down for a full description of it. il-2 would be similar but even worse.
i have no idea what a myostatin antibody would do at this point, but these tend to be extremely blunt tools. remember that antibodies in general work by marking individual cells or compounds for destruction by your immune system. given that myostatin in all likelihood has an extremely short halflife, it probably would do nothing.
i do know they've tested the genes of elite bodybuilders and found that myostatin mutations presently do not represent any part of the discrepency in size between them and the rest of the population. various (not necessarily mstn-/-) mutations in the gene just don't seem to be what's limiting muscle development in any of these individuals.
flex supposedly had one(sez balco, so take it for what it's worth). most did not. many individuals in the population have one. there are a bajillion different alleles for any individual gene, including myostatin. you can also be homozygous or heterozygous(as the german boy's parents almost certainly were for mstn+/-) for a given mutation. you should know that. a pure mstn-/- mutation is indeed rare in humans, no doubt.
http://www.musclephotos.com/myogene.html
one thing to note is the myostatin gene is *ridiculously* conserved across species. it's really kind-of surprising that it would be such a well-defended gene. apparently it's quite critical for proper function as a developing species for some reason.
yes, it will affect muscle mass dramatically. is it the limiting factor at this point? i sincerely doubt it. i haven't given any thought to what prevents the top fleet of bodybuilders from growing further but it's almost certainly not myostatin.
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=pubmed&dopt=Abstract&list_uids=11078093
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=pubmed&dopt=Abstract&list_uids=15083369
"Myostatin genotype did not explain the hypertrophic response to ST when all 32 subjects were assessed."
"Responses to the strength-training program were not associated with the ACE I/D genotype (ANCOVA 0.057< P<0.70)."
you can argue these aren't knockouts, which is very true. but you would still expect to see some degree of variation or correlation here if it were a strong limiting or determining factor for humans involved in resistance exercise, not to mention all the other drugs we play around with.
fyi, there is a very good way you can reduce your myostatin levels dramatically right now. go to the damn gym and train your brains out. amongst the many complex transformations in muscle that occur as a result of resistance exercise, a sharp drop in myostatin production is one of them.