Axolotl (Ambystoma mexicanum) lymphocytes produce and are growth-inhibited by transforming growth factor-beta.
Recombinant (r)TGF-beta 5, an isoform of TGF-beta thus far identified only in the frog, Xenopus' laevis, inhibited phytohemagglutinin (PHA)-induced mitogenesis of salamander (axolotl) splenocytes and thymocytes, and T cell growth factor-induced proliferation of splenic lymphoblasts. This inhibition could be reversed by incubating (r)TGF-beta 5 with an anti-TGF-beta 5 antibody, but not with an antibody directed against TGF-beta 2, another Xenopus-produced TGF-beta isoform. Acid-treated supernatants from cultures of PHA-stimulated axolotl splenocytes (PHA-SNs) inhibited proliferation of mink lung fibroblasts (MLF), cells whose growth is sensitive to all known isoforms of TGF-beta. This inhibition was reversed by incubating the supernatants with the anti-pan-specific TGF-beta antibody which neutralizes TGF-beta 1, TGF-beta 2, TGF-beta 3 and TGF-beta 5. This inhibition was unaffected by antibodies that specifically neutralize either TGF-beta 1, TGF-beta 2, TGF-beta 3 or TGF-beta 5. Acid-treated axolotl PHA-SNs also inhibited proliferation of PHA-stimulated freshly harvested axolotl spleen cells. Once again, this inhibition could be reversed by treating supernatants with an anti-pan-specific TGF-beta antibody but not with anti-TGF-beta 2 or anti-TGF-beta 5 antibodies. All these data are consistent with the hypothesis that axolotl lymphocytes secrete a previously unknown TGF-beta isoform.
Koniski
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A
Department of Microbiology, University of Rochester Medical Center, NY 14642, USA. cohen@uhura.cc.rochester.edu.
Cohen
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N
D000557:Ambystoma / Q000276:immunology*; D000818:Animals; D001681:Biological Assay; D008214:Lymphocytes / Q000276:immunology*; D008934:Mitogens / Q000032:analysis; D011994:Recombinant Proteins / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000276:immunology*
D008934:Mitogens; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta