DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.48120#0112
94 Molecular and Cell Biology of Autoantibodies and Autoimmunity
B7B but not to D, high IgG B'/B ELISA levels were not seen at any time, even
though IgM B'/B reactivities remained high during this follow-up period.
This study provides further evidence for the infrequent switch from IgM to
IgG of autoantibodies which react with epitope(s) unique to B7B. Furthermore,
it is possible that IgM autoantibodies to epitope(s) unique to the D polypeptide
might also be present.
Enzyme-Linked Immunosorbent Assay Using Isolated (U) Small
Nuclear Ribonucleoprotein Polypeptides as Antigens
Y. Takeda1, J. Chen \ G.S. Wang1, R.J. Wang1, S.K. Anderson1,
I. Pettersson2, S. Amaki1, and G. C. Sharp1
'University of Missouri, Columbia, MO 65212, USA
2Karolinska Institute, Stockholm, Sweden
Antibodies to U 1 ribonucleoprotein (RNP) in very high titers have a strong
association with mixed connective tissue disease (MCTD), and anti-Sm antibodies
have a high specificity for systemic lupus erythematosus (SLE). These autoan-
tibodies have been known to react with U small nuclear RNPs (snRNPs), and an-
ti-RNP antibodies immunoprecipitate U1 RNA, while anti-Sm antibodies im-
munoprecipitate Ul, U2, U4, U5, and U6 RNAs. Recent immunoblotting
studies have revealed that anti-RNP antibodies react with 68 K, A, and C
polypeptides, and anti-Sm antibodies react with B7B and D polypeptides. Since
immunoblotting is basically a qualitative assay, it is not suitable to investigate
quantitative reactivities of autoimmune sera to individual U snRNP polypeptides.
Thus, we have developed a quantitative ELISA for IgG and IgM antibodies using
isolated 68 K, A, B'/B and D polypeptides as antigens. These polypeptide an-
tigens for ELISA were eluted from gel after SDS-polyacrylamide electrophoreses
of U 1 snRNP affinity-purified from rabbit thymus extract. Purity and stability
of these polypeptide antigens were confirmed by re-electrophoresis of each eluted
polypeptide.
ELISA results using each U snRNP polypeptide were positively correlated
with immunoblotting results. We performed the ELISA using isolated U snRNP
polypeptides on sera from 59 anti-RNP-positive patients. Among the 59 patients,
33 had active MCTD, 5 had inactive MCTD, 12 had active SLE, and 9 had undif-
ferentiated connective tissue disease (UCTD). In the 68 K polypeptide ELISA, pa-
tients with active MCTD showed significantly higher reactivity than patients with
B7B but not to D, high IgG B'/B ELISA levels were not seen at any time, even
though IgM B'/B reactivities remained high during this follow-up period.
This study provides further evidence for the infrequent switch from IgM to
IgG of autoantibodies which react with epitope(s) unique to B7B. Furthermore,
it is possible that IgM autoantibodies to epitope(s) unique to the D polypeptide
might also be present.
Enzyme-Linked Immunosorbent Assay Using Isolated (U) Small
Nuclear Ribonucleoprotein Polypeptides as Antigens
Y. Takeda1, J. Chen \ G.S. Wang1, R.J. Wang1, S.K. Anderson1,
I. Pettersson2, S. Amaki1, and G. C. Sharp1
'University of Missouri, Columbia, MO 65212, USA
2Karolinska Institute, Stockholm, Sweden
Antibodies to U 1 ribonucleoprotein (RNP) in very high titers have a strong
association with mixed connective tissue disease (MCTD), and anti-Sm antibodies
have a high specificity for systemic lupus erythematosus (SLE). These autoan-
tibodies have been known to react with U small nuclear RNPs (snRNPs), and an-
ti-RNP antibodies immunoprecipitate U1 RNA, while anti-Sm antibodies im-
munoprecipitate Ul, U2, U4, U5, and U6 RNAs. Recent immunoblotting
studies have revealed that anti-RNP antibodies react with 68 K, A, and C
polypeptides, and anti-Sm antibodies react with B7B and D polypeptides. Since
immunoblotting is basically a qualitative assay, it is not suitable to investigate
quantitative reactivities of autoimmune sera to individual U snRNP polypeptides.
Thus, we have developed a quantitative ELISA for IgG and IgM antibodies using
isolated 68 K, A, B'/B and D polypeptides as antigens. These polypeptide an-
tigens for ELISA were eluted from gel after SDS-polyacrylamide electrophoreses
of U 1 snRNP affinity-purified from rabbit thymus extract. Purity and stability
of these polypeptide antigens were confirmed by re-electrophoresis of each eluted
polypeptide.
ELISA results using each U snRNP polypeptide were positively correlated
with immunoblotting results. We performed the ELISA using isolated U snRNP
polypeptides on sera from 59 anti-RNP-positive patients. Among the 59 patients,
33 had active MCTD, 5 had inactive MCTD, 12 had active SLE, and 9 had undif-
ferentiated connective tissue disease (UCTD). In the 68 K polypeptide ELISA, pa-
tients with active MCTD showed significantly higher reactivity than patients with