DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.48120#0113
Abstracts
95
other diseases. On the other hand, in the A polypeptide ELISA, active MCTD
and SLE patients did not show any difference in their reactivity. Since the typical
serologic feature of MCTD is a high titer by passive hemagglutination of an-
tibodies to extractable nuclear antigen (ENA-PHA), we compared the results of
ENA-PHA titers and 68 K polypeptide ELISA levels. Although the anti-68 K
ELISA levels correlated in general with ENA-PHA titers, there were some excep-
tions in which high ENA-PHA titers were associated with low anti-68 K ELISA
levels. This discrepancy might be due to the presence in ENA of antigens other
than the 68 K polypeptide. In the B7B and D polypeptide ELISAs, patients with
SLE showed higher reactivities than patients with other diseases.
In a comparison of clinical manifestation and U snRNP polypeptide ELISA
results, patients with myositis and esophageal hypomotility showed significantly
higher 68 K reactivity. Patients with renal disorder and patients without
Raynaud’s phenomenon showed higher B7B and D polypeptide reactivities.
Longitudinal observations performed on 6 patients with MCTD revealed that
IgG 68 K reactivity was related to disease activity.
We also utilized this ELISA for screening and characterization of human
monoclonal antibodies to U snRNPs. An IgM class antibody-producing human
lymphocyte cell line, designated Su-2E4, was isolated after Epstein-Barr virus
transformation of lymphocytes from a patient with MCTD. In ELISAs using U
snRNP polypeptides, Su-2E4 showed a high level of reactivity only in the case of
the IgM 68 K polypeptide ELISA. This reactivity was inhibited by 50% when
Su-2E4 was incubated with the 68 K polypeptide before being placed in antigen-
coated wells, confirming the specificity of Su-2E4. To investigate the epitope rela-
tionship between Su-2E4 and a murine anti-68 K monoclonal antibody, 2.73, we
preincubated 2.73 with the 68 K polypeptide-coated well before adding Su-2E4.
The binding of su-2E4 to the 68 K polypeptide was inhibited by 64% by prein-
cubation of the antigen with 2.73, suggesting that these two monoclonal an-
tibodies are directed to closely related epitopes.
These results suggest that this specific ELISA using isolated U snRNP
polypeptides is useful for the quantitative analysis of autoantibodies against these
polypeptides. Using this method, we obtained quantitative confirmation of the
relationship between IgG 68 K polypeptide reactivity and MCTD, and between
IgG B7B and D reactivities and SLE. Furthermore, this ELISA was useful for
screening of monoclonal antibodies to U snRNPs, and facilitated quantitative
competitive assays.
95
other diseases. On the other hand, in the A polypeptide ELISA, active MCTD
and SLE patients did not show any difference in their reactivity. Since the typical
serologic feature of MCTD is a high titer by passive hemagglutination of an-
tibodies to extractable nuclear antigen (ENA-PHA), we compared the results of
ENA-PHA titers and 68 K polypeptide ELISA levels. Although the anti-68 K
ELISA levels correlated in general with ENA-PHA titers, there were some excep-
tions in which high ENA-PHA titers were associated with low anti-68 K ELISA
levels. This discrepancy might be due to the presence in ENA of antigens other
than the 68 K polypeptide. In the B7B and D polypeptide ELISAs, patients with
SLE showed higher reactivities than patients with other diseases.
In a comparison of clinical manifestation and U snRNP polypeptide ELISA
results, patients with myositis and esophageal hypomotility showed significantly
higher 68 K reactivity. Patients with renal disorder and patients without
Raynaud’s phenomenon showed higher B7B and D polypeptide reactivities.
Longitudinal observations performed on 6 patients with MCTD revealed that
IgG 68 K reactivity was related to disease activity.
We also utilized this ELISA for screening and characterization of human
monoclonal antibodies to U snRNPs. An IgM class antibody-producing human
lymphocyte cell line, designated Su-2E4, was isolated after Epstein-Barr virus
transformation of lymphocytes from a patient with MCTD. In ELISAs using U
snRNP polypeptides, Su-2E4 showed a high level of reactivity only in the case of
the IgM 68 K polypeptide ELISA. This reactivity was inhibited by 50% when
Su-2E4 was incubated with the 68 K polypeptide before being placed in antigen-
coated wells, confirming the specificity of Su-2E4. To investigate the epitope rela-
tionship between Su-2E4 and a murine anti-68 K monoclonal antibody, 2.73, we
preincubated 2.73 with the 68 K polypeptide-coated well before adding Su-2E4.
The binding of su-2E4 to the 68 K polypeptide was inhibited by 64% by prein-
cubation of the antigen with 2.73, suggesting that these two monoclonal an-
tibodies are directed to closely related epitopes.
These results suggest that this specific ELISA using isolated U snRNP
polypeptides is useful for the quantitative analysis of autoantibodies against these
polypeptides. Using this method, we obtained quantitative confirmation of the
relationship between IgG 68 K polypeptide reactivity and MCTD, and between
IgG B7B and D reactivities and SLE. Furthermore, this ELISA was useful for
screening of monoclonal antibodies to U snRNPs, and facilitated quantitative
competitive assays.