V. Dimitriadou et al., Expression of functional major histocompatibility complex class II molecules on HMC-1 human mast cells, J LEUK BIOL, 64(6), 1998, pp. 791-799
Mast cells hold a key position in the defensive mechanisms against exogenou
s intruders. In this study, we investigated whether human mast cells expres
s functional major histocompatibility complex (MHC) class II molecules that
can transduce endogenous signals and present staphylococcal enterotoxin A
(SEA) to T cells. Similar to HMC-1 human mast cell line, umbilical cord blo
od-derived mast cells express HLA-DR, -DP and -DQ molecules on their surfac
e. MHC class II molecules expressed on HMC-1 cells bind significantly the S
EA (a natural MHC class II ligand), and their ligation with specific mAbs o
r with SEA, leads ultrastructural chages, suggesting their degranulation, R
ecognition of SEA-bound MHC class II molecules on HMC-1 mast cells by the T
cell receptor of K25 cells, an SEA-specific murine T cell hybridoma, trigg
ers significant IL-2 secretion by these T cell hybridomas. Hence, our data
point out the expression of functional MHC class II molecules on human mast
cells, reinforcing the implication of these cells in the defense mechanism
s of acquired immunity.