A. Erdei et al., COMPLEMENT PEPTIDE C3A INHIBITS IGE-MEDIATED TRIGGERING OF RAT MUCOSAL MAST-CELLS, International immunology, 7(9), 1995, pp. 1433-1439
The relationship between mast cells' secretory response to stimulation
via their type 1 Fc epsilon receptors (Fc epsilon RI) and that provid
ed by the C3a fragment of the complement system was investigated in th
e rat mucosal-type mast cell line RBL-2H3. These cells are known to be
unresponsive to the so-called 'peptidergic' stimulus provided by cati
onic agents, such as anaphylatoxins, neuropeptides or polyamines, We n
ow observed that C3a effectively inhibits the Fc epsilon RI clustering
induced secretion of RBL-2H3 cells. This inhibition is dose-dependent
and takes place at a C3a concentration range of 0.4-12.5 nM, i,e, at
least three orders of magnitude lower than those where this anaphylato
xin exerts its secretory stimulus to 'serosal' mast cells. In order to
identify where C3a interferes in the Fc epsilon RI coupling cascade,
we have studied its effect on the cells' protein phosphorylation patte
rn, hydrolysis of phosphatidyl inositides, transient rise in free cyto
solic Ca2+ ion concentration and Ca2+ uptake, All these processes were
found to be inhibited by a similar C3a concentration range.