Dialysis membranes inhibit in vitro release of beta-2-microglobulin from human lymphocytes

In the present study the effect of different dialysis membrane materials on in vitro beta 2-microglobulin (beta 2M) release by human lymphocytes was investigated. Lymphocytes were isolated from 11 long-term haemodialysis patients and 9 healthy controls. Cells were cultured either on flat sheet membranes made from Cuprophan, Hemophan and polyacrylonitrile or on polystyrol. beta 2M concentrations in the supernatant were measured at 3 and 7 days of culture, respectively. The beta 2M release from lymphocytes obtained from uraemic patients was almost identical with the release from healthy subjects. In the presence of all three membranes the release of beta 2M was less of what was produced on polystyrol. This held true for lymphocytes isolated from both healthy and uraemic subjects. As for the three membrane materials, the release of beta 2M into the supernatants was statistically not different when the adsorptive capacity of polyacrylonitrile was taken into account. However, there was a tendency for Cuprophan to exert the strongest inhibition, while Hemophan and polyacrylonitrile reduced beta 2M release to a lesser degree. Based on these data it seems that the increase in serum beta 2M which has been observed during dialysis with Cuprophan membranes is not caused by direct interaction of lymphocytes with Cuprophan membranes.