Observation of the effect of substance P on human T and B lymphocyte proliferation.

In the present experiment we attempted to confirm the specific stimulation of substance P (SP) on human T lymphocyte proliferation as reported by Payan et al. and to observe its effect on human B lymphocyte proliferation. As a result, no definite mitogenic effect of SP (10(-11) to 10(-7) M) was found on both human T and B cells, no significant influence of SP on the blastogenic response of T cells to Con A or PHA stimulation in a wide range of concentrations and no effect on proliferative response of B cells to Staphylococcus aureus Cowen strain I stimulation were shown. Payan's conclusion was based on percentage increase of 3H-TdR incorporation. But as the background cpm is generally very low, even 100 per cent increase would only indicate a very small cpm increase, so in this situation percentage increase might give false phenomenon, and only cpm could tell whether the effect was strong or weak. Thus, we believe that is the reason for our disagreement with Payan's conclusion.