DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.48120#0111
Abstracts
93
genic B'/B and D polypeptides by enzyme-linked immunosorbent assay
(ELISA).
Among 136 sera positive for antibodies to U snRNPs, the ratio of IgM and
IgG ELISA levels (M/G) of B'/B was higher than M/G of D (P<0.05). Further-
more, sera with high M/G of B'/B showed low IgM D ELISA levels. These results
indicate that there are some sera with IgM B'/B but neither IgM D nor IgG B'/B
reactivies. From these results, it appeared that there might be IgM autoantibodies
directed against epitope(s) in B'/B polypeptides that differ from the Sm-epitope(s)
shared with the D polypeptide, and that these antibodies might infrequently
switch to IgG antibodies. In order to confirm this hypothesis, we performed com-
petitive ELISAs using B'/B and D polypeptides.
In IgM B'/B ELISAs with inhibition by the D polypeptide performed on 99
sera with significant IgM B'/B reactivities (>mean + 5SD of negative control
sera), 53 sera showed less than 40% inhibition ([ELISA level without inhibition
- level with inhibition]/level without inhibition), 21 showed between 40% and
60%, and 25 showed more than 60% inhibition. Furthermore, sera with less than
40% inhibition showed lower IgG B'/B ELISA levels than sera with more than
60% inhibition (P<0.05).
It was possible that these IgM reactions with B'/B polypeptides not inhibited
by the D polypeptide might be due to non-specific reactions. Therefore, to rule
out this possibility, IgM B'/B competitive ELISAs with inhibition by B'/B
polypeptides were performed on 37 sera which had low % inhibition by the D
polypeptide. All 37 sera showed more than 60% inhibition, indicating that these
IgM reactivities against B'/B were specific.
In order to compare the IgM and IgG reactivities against B'/B polypeptides,
we performed IgG B'/B competitive ELISAs with inhibition by the D polypeptide
on the 23 sera with the highest IgG B'/B ELISA levels. Among the 23 sera, none
showed less than 40%, 7 showed 40%-60%, and 16 showed more than 60% in-
hibition. On the other hand, in IgM B'/B competitive ELISAs with inhibition by
the D polypeptide on the 23 sera with the highest IgM B'/B ELISA levels, 12 sera
showed less than 40%, 3 showed 40-60%, and 8 showed more than 60% inhibi-
tion. These results suggest that the IgG antibodies to the B'/B polypeptides were
mainly directed to Sm-epitope(s) shared with the D polypeptide: however, among
IgM-reacting sera, there were a significant number whose IgM antibodies were di-
rected to epitope(s) not shared with the D polypeptide.
Ten sera had significant IgM reactivities against both B'/B and D polypep-
tides, but less than 40% inhibition by the D polypeptide in IgM B'/B ELISAs.
Among them, 3 sera showed less than 40% inhibition in IgM D ELISAs with
competition by B'/B, suggesting that IgM reactivities to the D polypeptide in
these sera were not related to epitope(s) shared with the B'/B polypeptides. By im-
munoblotting or ELISA without competition, these sera cannot be distinguished
from sera with IgM reactivity against epitope(s) shared by B'/B and D. In
longitudinal studies over more than 5 years in 3 patients with IgM reactivities to
93
genic B'/B and D polypeptides by enzyme-linked immunosorbent assay
(ELISA).
Among 136 sera positive for antibodies to U snRNPs, the ratio of IgM and
IgG ELISA levels (M/G) of B'/B was higher than M/G of D (P<0.05). Further-
more, sera with high M/G of B'/B showed low IgM D ELISA levels. These results
indicate that there are some sera with IgM B'/B but neither IgM D nor IgG B'/B
reactivies. From these results, it appeared that there might be IgM autoantibodies
directed against epitope(s) in B'/B polypeptides that differ from the Sm-epitope(s)
shared with the D polypeptide, and that these antibodies might infrequently
switch to IgG antibodies. In order to confirm this hypothesis, we performed com-
petitive ELISAs using B'/B and D polypeptides.
In IgM B'/B ELISAs with inhibition by the D polypeptide performed on 99
sera with significant IgM B'/B reactivities (>mean + 5SD of negative control
sera), 53 sera showed less than 40% inhibition ([ELISA level without inhibition
- level with inhibition]/level without inhibition), 21 showed between 40% and
60%, and 25 showed more than 60% inhibition. Furthermore, sera with less than
40% inhibition showed lower IgG B'/B ELISA levels than sera with more than
60% inhibition (P<0.05).
It was possible that these IgM reactions with B'/B polypeptides not inhibited
by the D polypeptide might be due to non-specific reactions. Therefore, to rule
out this possibility, IgM B'/B competitive ELISAs with inhibition by B'/B
polypeptides were performed on 37 sera which had low % inhibition by the D
polypeptide. All 37 sera showed more than 60% inhibition, indicating that these
IgM reactivities against B'/B were specific.
In order to compare the IgM and IgG reactivities against B'/B polypeptides,
we performed IgG B'/B competitive ELISAs with inhibition by the D polypeptide
on the 23 sera with the highest IgG B'/B ELISA levels. Among the 23 sera, none
showed less than 40%, 7 showed 40%-60%, and 16 showed more than 60% in-
hibition. On the other hand, in IgM B'/B competitive ELISAs with inhibition by
the D polypeptide on the 23 sera with the highest IgM B'/B ELISA levels, 12 sera
showed less than 40%, 3 showed 40-60%, and 8 showed more than 60% inhibi-
tion. These results suggest that the IgG antibodies to the B'/B polypeptides were
mainly directed to Sm-epitope(s) shared with the D polypeptide: however, among
IgM-reacting sera, there were a significant number whose IgM antibodies were di-
rected to epitope(s) not shared with the D polypeptide.
Ten sera had significant IgM reactivities against both B'/B and D polypep-
tides, but less than 40% inhibition by the D polypeptide in IgM B'/B ELISAs.
Among them, 3 sera showed less than 40% inhibition in IgM D ELISAs with
competition by B'/B, suggesting that IgM reactivities to the D polypeptide in
these sera were not related to epitope(s) shared with the B'/B polypeptides. By im-
munoblotting or ELISA without competition, these sera cannot be distinguished
from sera with IgM reactivity against epitope(s) shared by B'/B and D. In
longitudinal studies over more than 5 years in 3 patients with IgM reactivities to