Background: We have shown in vitro AL-amyloid formation by human mesangial cells (MCs) exposed to amyloldogenic light chains (AL-LC), in the presence and absence of amyloid enhancing factor. TGF-B has been identified as an important mediator of matrix deposition and glomerulosclerosis. We investigated TGF-B activity in this in vitro model. Methods: Human MCs grown on chamber slides were treated with an AL-LC (10ug/ml of media) for four days. Cells incubated with media alone were used as controls. The AL-LC was obtained from the urine of a patient with renal amyloidosis. Amyloid formation was evaluated using hematoxylin and eosin and Thioflavin-T stains. TGF-B activity in culture supernatans was assayed by determining colony formation by NRK cells. Results: Al-amyloid formation in vitro by human MCs exposed to an AL-LC was confirmed. TGF-B activity was significantly lower in supernatans of cells cultures treated with the AL-LC when compared to control cells (61 vs 109 colonies). Conclusions : In vitro amyloid formation by human MCs is associated with low TGF-B activity. These findings suggest that low TGF-B activity may be playing a permissive role for amyloidogenesis to occur.