Staphylococcus enterotoxins and toxic shock syndrome toxin-1 (TSST-1)
are members of the family of staphylococcal exoproteins (SE) which bin
d specifically to HLA class II molecules and certain V beta T cell rec
eptor phenotypes. These bacterial products have been termed ''superant
igens'' due to their capacity to stimulate a greater proportion of T l
ymphocytes than peptide antigens without a requirement for antigen pro
cessing. The SE stimulate monocytes to secrete IL-1 and TNF-alpha and
affect B lymphocyte proliferation in response to anti-human IgM and Ig
production by PBMC. The current study concerns the transmission of si
gnals in human B lymphocytes following fixation of TSST-1. Activation
of both PLC and PKC are observed while intracellular calcium levels re
main unchanged. Levels of HLA class II mRNA were increased suggesting
that a pathway leading to activation was triggered. This study therefo
re identifies some of the second messengers involved after SE fixation
on HLA class II molecules and suggests that the signals transmitted v
ia class II antigens as well as those via the TCR may have a role in t
he physiological responses to bacterial superantigens.