The elevation of plasma soluble tumor necrosis factor receptor levels by TNF induction therapy for patients with malignancy.

Soluble tumor necrosis factor receptor (sTNF-R) is known to inhibit patient immunity via specific binding with the TNF molecule. To examine the possible involvement of sTNF-R in cancer immunotherapy, the plasma levels of sTNF-R of both 55 kDa and 75 kDa origins were estimated when TNF was induced in patients with malignancy using both a polysaccharide preparation (Lentinan) and a streptococcal preparation (OK-432). The pretreatment plasma levels of the 55 kDa and 75 kDa sTNF-R were 1.04 +/- 0.53 and 1.06 +/- 0.34 ng/ml (mean +/- SE), respectively. The plasma levels of TNF were undetectable before treatment. The plasma sTNF-R levels peaked 2 h after the administration of OK-432 and followed the same pattern as the TNF levels in plasma. Both TNF and sTNF-R nearly returned to pretreatment levels at 16 h after the induction of TNF. The peak plasma levels of the 55 kDa and 75 kDa sTNF-R were 2.46 +/- 0.95 and 3.03 +/- 0.88 ng/ml, respectively, but they did not correlate with the plasma TNF levels. When peripheral white blood cells were cultured with the addition of lipopolysaccharide in vitro, an elevation of the 72 kDa sTNF-R was detected. Thus, the plasma source of this soluble receptor can at least be partly attributed to the white blood cells. However, the 55 kDa sTNF-R showed little increase in the cultures, and its source remains unknown. We should therefore be aware of the elevation of plasma sTNF-R levels by the induction therapy of TNF for patients with malignancies because of the immunosuppressive effect of sTNF-R.