192aa rHGH & developing antibodies
I often hear some of the bros (JB) here debating about 191aa rHGH vs.192aa and how 192aa will make you develope antibodies, however never saw any studies on it. Here is an article I found, keep in mind I merely copy and paste from another board, this was not my experience.
This is the latest study done that I know of that addresses this issue. I have always said do not use 192 aa rHGH if you have a choice. It does appear now however that our initial concerns related to the development of antibodies to HGH from the use of methionyl human growth hormone, and the role these antibodies play, may have been unfounded. At least to the point of being a near statistical impossibilty. I remember when all we had we was Protropin. I know many pros, one of whom was my training partner, from that era who used 192aa rHGH successfully. I remember when Humatrope became available, it was common thought that Protropin produced antibodies to GH in 30-35% of users. I never saw anything to support that, regardless, everyone who could switched to Humatrope. There was really no great debate. No one used Protropin unless they had no other choice. So, the use of methionyl human growth hormone became nearly obsolete until the Chinese rHGH market sprung up. Now, we have debate. And I think rightfully so. The truth is, GH antibody binding properties below 2mg/L show no negative effects whatsoever. GH antibody binding properties in excess of 2mg/L have been shown to cause attenuation. But, recent evidence suggests that this occurs in only 0.4% of users. Of those 0.4% only a few will actually have attenuative effects. So, it is estimated that only 0.1% of users will experience any negative effects from the production of GH antibodies. So, while it is possible, it is very unlikely. This crap about the purity of Kexing being the reason why the immune response is not a concern is just that though, crap. Kexing does not produce a methionyl rHGH with greater purity than Genetech, no way. The study below also debunks this notion. Anyway, this is not an endorsement of Kexing. I know of no one who uses it (I know a great many pros and top amateurs) and I don't nor have I ever used it myself. I think I've given enough information for people to make their own decision. I can't speak for Kexing though.
The use of an animal immunogenicity model in the development of Protropin somatrem (methionyl human growth hormone).
Jones AJ.
Department of Analytical Chemistry, Genentech Inc., South San Francisco, CA 94080, USA. [email protected]
The clinical development of methionyl human growth hormone, with particular emphasis on immunogenicity and the effects of antibody development, are summarized. In an animal model in rhesus monkeys, the immunogenicity of dinical preparations was reduced by the inclusion of additional purification steps in the manufacturing process. The immunogenic response in patients was also decreased by these improvements. No safety consequences related to antibody formation were observed and the occurrence of growth attenuation due to antibodies was found to be extremely low (<0.1%). The data suggest that the immunogenicity was not due to the N-terminal methionine or E. coli protein impurities: rather it was probably caused by small amounts of growth hormone with subtle structural alterations whose nature remains unknow
