The magnitude of the changes in a variety of blood constituents on exposure to the dialysis membrane has been used as an index of “biocompatibility,” and dialyzer reuse has been postulated to improve biocompatibility by attenuating these changes. We studied the hemodialysis-induced changes in the in vitro production of interleukin-1 receptor antagonist (IL-1Ra) and interleukin-1β (IL-1β) by peripheral blood mononuclear cells (PBMCs), and compared the effect of first use and reuse of cuprophan membranes on these changes. Studies were performed during dialysis with first use and third reuse of the same kidney. The cell content and production of IL-1Ra and IL-1β by unstimulated and endotoxin- or IgG-stimulated PBMCs were studied just prior to dialysis, and from the afferent and efferent limbs of the blood circuit 15 minutes after the start of dialysis. Interleukin-1 receptor antagonist and IL-1β were measured by specific radioimmunoassay and are expressed as picograms per 2.5 × 106 PBMCs. Fifteen minutes after the start of dialysis, the number of PBMCs harvested from 10 mL of blood decreased from 19.8 ± 4.7 × 106 predialysis to 14 ± 3 × 106 (P = 0.05). Interleukin-1 receptor antagonist production by PBMCs from the afferent limb of the dialysis circuit was lower (P < 0.0001) than predialysis in unstimulated (2,333 ± 932 pg v 2,600 ± 781 pg), endotoxin-stimulated (8,580 ± 2,606 pg v 29,025 ± 6,248 pg), and IgG-stimulated cells (3,021 ± 824 pg v 23,971 ± 8,892 pg). Interleukin-1β production by endotoxin-stimulated PBMCs from the afferent limb of the dialysis circuit (1,790 ± 440 pg) was also significantly lower (P < 0.0001) than predialysis (8,781 ± 1,407 pg). However, the production of both IL-1Ra and IL-1β by PBMCs from the efferent limb of the dialysis circuit was not significantly different from the production of both IL-1Ra and IL-1β by PBMCs from the afferent limb. The decrease in the number of PBMCs harvested from 10 mL of blood after initiation of dialysis with reused dialyzers (from 19 ± 4 × 106 to 12 ± 3 × 106) was not significantly different from that during first use (from 25 ± 7 × 106 to 15 ± 42 × 106). Furthermore, the decline in endotoxin-stimulated IL-1Ra production during reuse (from 23,086 ± 5,272 pg to 7,261 ± 2,122 pg) was not significantly different from that during first use (from 33,300 ± 10,178 pg to 9,963 ± 3,677 pg). The decline in the endotoxin-stimulated IL-1β production during reuse (from 7,714 ± 1,679 pg to 1,779 ± 629 pg) was also not significantly different from that during first use (from 8,000 ± 1,764 pg to 1,811 ± 657 pg). In summary, the initiation of hemodialysis is accompanied by a reduction in the number of PBMCs harvested from blood and the capacity of these cells to produce IL-1Ra and IL-1β. This suggests that membrane exposure leads to sequestration of an active subset of PBMCs, possibly in the microcirculation. Reprocessing of dialyzers with glutaraldehyde and sodium hypochlorite does not attenuate the dialysis-induced alterations in PBMC number or production of cytokines. © 1993, National Kidney Foundation, Inc.. All rights reserved.
