5.0 RBL-2H3 cell line
In mast cell research, the most
common animal cell line used is the RBL-2H3 cell line59. The RBL cells were generated from rats that were
injected with the chemical carcinogen β-chlorethylamine to induce
basophilic leukemia 60. The RBL cells were adapted to
suspension cell culture (named RBL-1) and can specifically bind IgE to
their surface membrane 61,62. Nevertheless, neither an
IgE/antigen trigger nor chemical stimulation by a Ca2+ionophore were able to cause RBL-1 to release histamine63. A responsive subline known as RBL-2H3 that
degranulated in response to an IgE trigger was successfully isolated
from subsequent cloning of RBL cells in 1981 64. These
cells were a great model for understanding the FcεRI signaling cascades
as they could be cultured in huge numbers to examine the characteristics
and binding properties of IgE which will lead to the signaling pathways
involved in degranulation 65.
RBL-2H3 cells were widely employed as a mast cells model shortly after
they were formed. Unquestionably, RBL-2H3 cells have the advantage of
being a cell line that is simple to cultivate due to its short doubling
time (18-24 h), enabling researchers to obtain a high number of
homogenous cells easily. However, their suitability and credibility were
eventually questioned 66,67. In the early years of RBL
cells establishment, a variant with impaired cromoglycate binding had
been identified in a population of RBL-2H3 which suggest that the cell
line may not be fully homogenous 68. Although research
reports frequently referred to RBL cells as mast cell line, it was in
fact derived from basophils. Additionally, the cell line was lack of
consistency as to the physiology of basophils or mast cells as well as
findings between other research groups utilizing the same cell line66. Mast cells and basophils are two different but
functionally related cell types that are essential in type I
hypersensitivity. Granulocyte basophils circulate, whereas mature mast
cells are only found in tissues at the interfaces with external
environment, such as the lungs, skin, and mucosal surfaces69. Despite their similarities, it was suggested that
the two cell types descended from distinct lineages70,71. Nonetheless, numerous arguments suggested that
they may share a common origin 72,73.
Nevertheless, RBL-2H3 cells have been successfully used in
investigations on IgE binding to FceRI receptors and subsequent
downstream processes 66,74. The expression of rat mast
cell protease II (RMCP-II) 75 and a similar expression
of the c-kit receptor tyrosine kinase 76 in RBL-2H3
cells comparative to human HMC-1 and murine P-815 mast cells were one of
the few aspects of mast cell physiology that supports the notion that
RBL-2H3 cells can model mast cells. Moreover, numerous studies have
found similarities between the exocytosis mechanisms of bone marrow mast
cells and RBL cells involving SNARE proteins, designating RBL cells as a
suitable model for research on MC exocytosis 59.