6.0 Alternative options for in vitro mast cell studies
Apart from the mentioned cell lines, there are also other alternative
options for in vitro mast cell studies in allergy albeit not as
commonly reported. One of them is the Immortalized Human Mast Cell Line
(LUVA). This cell line was first identified and characterized by Laidlaw
and her collegues in 2011 114. The cells were grown
from CD34+-enriched mononuclear cells derived from the peripheral blood
of a donor with aspirin exacerbated respiratory disease114. The authors mentioned that this cell line can be
maintained without stem cell factor to survive and proliferate without
further addition of any growth factors for approximately 2 years. In
addition, LUVA cells also display high levels of normally signaling
c-kit, metachromatic cytoplasmic granules, and FcεRI114. These cells will prove valuable for functional
human mast cell studies as they can be induced to degranulate and
release various allergic mediators such as β-hexosaminidase,
prostaglandin D2, thromboxane A2, and MIP-1β.
Another human mast cell line that is suitable for allergy studies is the
ROSAKIT mast cells. This cell line was first reported
in 2014 115. Unlike LUVA cells, these cells require
stem cell factor to survive and proliferate with a doubling time of 24 h115. ROSAKIT cell also has
functional IgE receptors which allows it to be easily activated to
release mediators whenever FcεRI crosslinking happens115. Apart from activation through IgE receptors, this
human mast cell line can also be induced by means of calcium influx. A
reported study showed that the ROSAKIT cell induction
using calcium ionophore A23187 was able to release 80% of
β-hexosaminidase as compared to using IgE-FcεRI which only releases
approximately 38% of the enzyme after 1 h induction115.
Apart from that, secondary mast cell lines from mouse origin such as
MC/9 and P815 cell lines are also available. The MC/9 is a cloned mast
cell line derived from the fetal liver of a (B6 × A/J)F1 mouse116. These cells can be sensitized to specific
antigens by incubating them with IgE having the desired antigenic
specificity, resulting in the release of soluble mediators such as
histamine and leukotrienes when induced 117. A
reported study by Jin et al. (2019) has also induced these cells using
PMA (50 nM) and A23187 (1 μM) for 24 h to measure the release of
histamine and LTC4 levels 118. P815 cells, on the
other hand were isolated from a mouse with mastocytoma in 1957118,119. These cells do not express the IgE high
affinity receptor and, therefore, can only be activated independent of
the IgE pathway. However, they do express fragment crystallizable gamma
receptor II (FcγRII) and could bind the Fc portion of mouse IgG
antibodies through their fragment antigen-binding (Fab) which may
recognize NK cells activating receptors leading to target cell lysis120. In addition, one study reported the use of C48/80
and CI to induce degranulation in P815 cells to release allergic
mediators such as IL-4 and histamine 121.