Modulation of B Cell Responses by Glycolipid Released from Antigen-Stimulated T Cells

Abstract

Mice immunized with either 10⁹ or 10⁶ SRBC were used as a source of T suppressor (Ts) cells and T helper (Th) cells, respectively. T cells were prepared by purification on glass wool and nylon wool columns and were cultivated at 37°C for 3 days. The suppressive or helper effects of the conditioned medium obtained from the T cells were determined in spleen cell cultures by a Jerne-plaque assay. Addition of suppressor medium (Ts-M) to a spleen cell assay was modulatory in that it delayed the normal response time by several days. Thy-1 and G_M1 ganglioside were associated with the modulatory substance because a normal response could be obtained by treatment of the Ts-M with anti-Thy-1.2 or anti-G_M1 ganglioside sera. Addition of helper T cell medium (Th-M) significantly enhanced anti-SRBC PFC response but anti-Thy-1 or anti-G_M1 ganglioside sera had no effect on the helper activity of Th-M. Glycolipids were isolated from Ts-M and Th-M, formulated into liposomes, and were added to PFC assay. A ganglioside isolated from Ts-M with the thin layer mobility (R_f) of brain G_M1 ganglioside was found to inhibit anti-SRBC-plaques. Other glycolipids from Ts-M were not inhibitory and none of the glycolipids isolated from Th-M were inhibitory under our assay conditions. The modulatory activity of Ts-M and the isolated glycolipid was not antigen specific and could be neutralized with anti-Thy-1 or anti-G_M1 sera. These findings demonstrate that the modulatory (or static) capacity of Ts-M isolated from cultures of partially purified T cells is associated with a cell product, probably a membrane complex, containing Thy-1 antigen and modulatory glycolipid.