The requirement for esterase activation in T cell replacing factor (TRF)-induced IgG production in a human B blastoid cell line

Involvement of stimulus-activatable serine esterase in the process of TRF-induced IgG production in a human B blastoid cell line (CESS) was demonstrated. Addition of DFP or PMSF (1 x 10^-3 M to 1 x 10^-5 M) showed a dose-dependent inhibitory effect on TRF-induced IgG induction in CESS cells. Other organophosphorous inhibitors, such as p-NPEPP and PEPP, were also effective, but a non-phosphorylating analogue of DFP, DMP, was not inhibitory. Simultaneous addition of DFP with TRF showed the inhibitory effect, and the inhibition was irreversible. However, pretreatment of the cells with DFP did not abrogate TRF-induced IgG production. In synchronized cells, signals provided by TRF could be transduced only when cells were in the G₁-phase, and DFP showed an inhibitory effect only when it was added to cells in the G₁-phase with TRF. One amino acid derivative (AAME) partially inhibited TRF-induced IgG production.