LAMP-1 and LAMP-2, but not LAMP-3, are reliable markers for activation-induced secretion of human mast cells.
BACKGROUND
Mast cells are resident tissue cells that induce anaphylactic reactions by rapidly releasing mediators after antigen-mediated cross-linking of immunoglobulin E receptors. In the similarly active peripheral blood basophilic leukocyte, lysosome-associated membrane protein 3 (LAMP-3; CD63) has been described as an activation marker, but LAMPs have not been investigated in normal tissue mast cells.


METHODS
Intra- and extracellular expressions of LAMP-1 (CD107a), LAMP-2 (CD107b), and LAMP-3 (CD63) were analysed by flow cytometry, immunocytochemistry, and functional assays in unstimulated and stimulated leukemic human mast cell line 1 (HMC-1) and skin mast cells.


RESULTS
On flow cytometry, all mast cells expressed LAMP-3 at their cell membranes, whereas LAMP-1 and LAMP-2 were barely detectable (HMC-1 cells) or expressed at low levels (<10% of skin mast cells). After fixation and permeabilisation, high intracellular levels of all three LAMPs were noted in both cell types. After stimulation, a rapid translocation of intracellular LAMPs to the cell membrane, with an associated release of histamine, leukotriene C(4) and prostaglandin D(2), was ascertained in skin mast cells only.


CONCLUSIONS
These results show that LAMP-1 and LAMP-2 are activation markers for normal mast cells. The lack of LAMP translocation after activation of leukemic mast cells may be related to maturation or malignancy-associated defects of these cells.
Grützkau
Andreas
A
Departments of Dermatology and Allergy, Humboldt University, Campus Charité Mitte, Berlin, Germany. gruetzkau@drfz.de
Smorodchenko
Alina
A
Lippert
Undine
U
Kirchhof
Loreen
L
Artuc
Metin
M
Henz
Beate M
BM
D015703:Antigens, CD / Q000378:metabolism*; D015415:Biomarkers; D002402:Cathepsin D / Q000378:metabolism; D002478:Cells, Cultured; D005434:Flow Cytometry; D006801:Humans; D052118:Lysosomal-Associated Membrane Protein 1; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D059666:Lysosomal-Associated Membrane Protein 3
D015703:Antigens, CD; D015415:Biomarkers; D002402:Cathepsin D; D052118:Lysosomal-Associated Membrane Protein 1; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C489116:LAMP1 protein, human; C114233:LAMP3 protein, human; D059666:Lysosomal-Associated Membrane Protein 3