Superantigen disruption of CD8+ T and B lymphocyte homeostasis.

Superantigens (SAgs) activate TH cells and induce their differentiation into cytokine-producing effector cells. Supranormal cytokine production is characteristic of SAg-induced polyclonal TH activation. Study of this interaction has focused upon TH cell function to the relative exclusion of other lymphocyte populations. SAgs also impact cells dependent upon TH cells for their differentiation and disrupt the normal homeostasis of the immune system. In this report, several changes in lymphocyte biology that result from SAg activation of TH cells are described. SCID mice, reconstituted with the SAg-expressing cells of DBA/2J mice, were employed as secondary recipients of SAg-reactive TH cells. Significant increases in serum IgM and IgG2a production were noted after the transfer of SAg-reactive It cells. Both B and CD8 T lymphocyte numbers increased with those of CD8 T cells surpassing levels found in normal mice. These results illustrate the ability of the TH-SAg interaction to disrupt B and CD8+ T lymphocyte homeostasis.