See the following reference on the discordance between MY4 and LeuM3
epitopes, in relation to LPS binding capacity. I include the abstract.
Basically, there are some monocyte cell lines which can bind My4 but not
LeuM3. Interestingly, this pattern (My4+ LeuM3- UCHM1-) is also seen in
airway DC and possibly blood DC precursors as well (ref.2), which suggests
another phenotype possibility for your patient (although these are not to
my knowledge CD15+).
1. T. Pedron, R. Girard and R. Chaby
Variation of LPS-binding capacity, epitope expression, and shedding of
membrane-bound CD14 during differentiation of human monocytes
Journal of Immunology 1995 155 (3): 1460-71
The myeloid differentiation Ag CD14 is considered to play a critical role
in the binding of LPS to monocytes. To determine if differences in
LPS-binding capacities of cells could reflect a variability of CD14
molecules, we analyzed the interactions of various reagents with these
molecules in human blood monocytes and in promyelocytic (HL60) and
monocytic (THP-1) cell lines. The expression of CD14 epitopes was analyzed
with the fluorescent anti-CD14 mAbs My4 and LeuM3. Expression of
LPS-binding sites (LPS+ molecules) was detected with LPS-FITC. THP-1 cells
stimulated with calcitriol (VitD3), as well as the majority of blood
monocytes (50-90%) were My4+/LPS+. However, untreated THP-1 cells, and a
substantial population (10-50%) of human monocytes from healthy donors,
were My4+/LPS-, thus suggesting the existence of CD14 isoforms with
different LPS-binding capacities. In line with this assumption, monocytes
stimulated with PMA selectively shed LeuM3+ molecules, but almost no My4+
and LPS+ constituents. Analysis of monocytes after treatment with
phosphatidylinositol-specific phospholipase C indicated that among CD14
molecules with LPS-binding capacity, some are susceptible and others are
resistant to the enzyme, each type being mainly expressed by a different
monocyte subset. Studies of uninduced and chemically induced THP-1 cells
showed that wheat-germ agglutinin blocked the binding of My4 to
constitutive, but not to chemically inducible CD14. The overall results
suggest the existence of at least three different forms of CD14, which may
reflect different stages of cell maturation.
2. J. M. van Haarst, H. J. de Wit, H. A. Drexhage and H. C. Hoogsteden
Distribution and immunophenotype of mononuclear phagocytes and dendritic
cells in the human lung
American Journal of Respiratory Cell & Molecular Biology 1994 10 (5): 487-92
______________________________________________
Dr William Smith
Institute for Child Health Research
(Company Limited by Guarantee ACN 009 278 755)
Subiaco, Western Australia, 6008
PO Box 855 West Perth WA 6872
Ph 61 8 9340 8792/8388, Fax 61 8 9388 3414
email williams@ichr.uwa.edu.au
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