Isoform specificity of commercially-available anti-TGF-beta antibodies

The transforming growth factor-beta (TGF-beta) cytokine family has importan t and complex effects on many biologic processes. Mammals have three TGF-be ta isoforms which differ in their primary amino acid sequence, receptor bin ding characteristics, distribution, and function. Characterization of TGF-b eta production and localization is critically dependent upon appropriate re agents, including antibodies. We have analyzed the isoform specificity of e ight commercially-available TGF-beta antibodies, including one monoclonal a ntibody and seven polyclonal antibodies. We carried out semi-quantitative W estern blot analysis using recombinant TGF-beta 1, beta 2, and beta 3 as ta rgets. We found that sensitivity and isoform specificity are dependent in p art upon the presence or absence of reducing conditions. The antibodies tes ted showed a broad range of sensitivity, with an ability to detect 50 pg to 20 ng. Cross-reactivity with another, incorrect isoform was seen with seve ral antibodies, and ranged from 0.2% to 42%. Nevertheless, we identified TG F-beta antibodies directed against each isoform which provide moderate-to-h igh sensitivity and specificity when used in Western blot analysis. These r esults may have relevance for investigators who wish to detect particular T GF-beta isoforms with techniques other than Western blot analysis, particul arly when these techniques involve denatured proteins. (C) 1999 Elsevier Sc ience B.V. All rights reserved.