Reactivity of anti-IgG subclass mAbs against all possible
combinations of IgG1-4 subclass protein
There are 15 possible combinations of positivity to the subclass protein
(such as IgG1 alone, IgG1+2, IgG1+2+3, etc). Table 2 shows the
reactivity of the different anti-IgG subclass mAbs against the 15
possible combinations of IgG1-4 subclass protein. We observed 9 distinct
anti-IgG subclass mAbs reactivity pattern groups instead of the 15
expected ones if the all mAbs were monospecific. Three anti-IgG subclass
mAbs patterns of reactivity corresponded to a unique combination of IgG
subclass protein. The anti-IgG subclass mAbs reactivity pattern of group
1, 2, and 3 identified IgG1, IgG4, IgG1+4, respectively. In contrast, 6
anti-IgG subclass mAbs patterns of reactivity corresponded to two
different combinations of IgG subclass protein. In group 4, the anti-IgG
subclass mAbs pattern of reactivity reveals that the anti-IgG subclass
mAbs cannot distinguish between IgG2 only and IgG1+2. Similarly in
groups 5 and 6, the anti-IgG subclass mAbs pattern of reactivity shows
that IgG3 only and IgG1+3, and IgG2+4 and IgG1+2+4, respectively, cannot
be distinguished. Although the anti-IgG subclass mAbs pattern of
reactivity in group 7, 8 and 9 can be distinguished, the differences
lies in the MFI intensity, which can be challenging to point out,
particularly if the concentration of the IgG subclass protein is high.
It is important to note that the monospecificty of anti-human-IgG3 mAb
(clone: HP6050) implies that positivity indicates the presence of IgG3
proteins. Last, using clones HP6001, HP6014, HP6050 and HP6025/HP6023
can distinguish the 9 pattern of reactivity detected with all the
anti-IgG subclass mAbs tested.