No soluble common cytokine receptor gamma chain (gamma(c)) in activated human lymphocyte cultures-comparison with soluble IL-2Ralpha.

The presence of a soluble form of the common cytokine receptor gamma chain (gamma(c)) in cell free supernatants from unstimulated and 1-6 days PHA stimulated peripheral blood lymphocyte (PBL) cultures was analyzed using a sandwich ELISA. No naturally produced soluble gamma(c) could be detected in these cell free culture supernatants, although a sensitivity in the nanogram range was achieved for recombinant baculovirus expressed human soluble gamma(c) with this assay (detection limit 0.2 ng hIL-2 sRgamma). Analysis of the very same supernatants for soluble IL-2Ralpha demonstrated increased concentrations (up to 20.4 ng/ml) of this other IL-2R member. The membrane-associated form of the common cytokine receptor gamma chain was detected in cell lysates prepared from stimulated PBL at a concentration of 3.5 ng per 0.5 x 10(6) cells. Analysis of a small panel of serum samples from patients with different disorders verified that the soluble form of hIL-2Ralpha, but not hIL-2 sRgamma, can be detected, which thereby strongly suggests that the human soluble gamma(c) seems to be a valuable marker only for a limited number of clinical disorders.