116 Molecular and Cell Biology of Autoantibodies and Autoimmunity
Reference
1. Krapf, F. E., Herrmann, M., Leitmann, W., Kalden, J. R.: Clin. Exp. Immunol, (in
press)
Heterogeneity of the Ro(SSA) Antigen and the Autoanti-Ro (SSA)
Response: Evidence for 4 Antigenically Distinct Forms
M. Reichlin and Y. Itoh
University of Oklahoma Health Sciences Center, Oklahoma Medical Research
Foundation, Oklahoma City, OK 73104, USA
Precipitating antibodies to the Ro (SSA) antigen occur in 40% of systemic
lupus erythematosus (SLE) patients and 40-70% of patients with primary
Sjogren’s Syndrome. Previous work has shown that lymphocytes contain
2 Ro (SSA) antigens with protein moieties of 60 kD and 52 kD M.W. (J. Exp.
Med. 167, 1560- 1571, 1988). We have reported that red cells contain 2 analogous
but antigenically distinct Ro (SSA) molecules of M. W. 60 kD and 54 kD (J. Clin.
Invest. 83, 1293-1298, 1989). Of 43 sera with precipitating anti-Ro(SSA), some
bind only one of the 4 isoforms in Western blot analysis. Moreover 42 of the 43
anti-Ro (SSA) bind 1 or more of the 4 Ro (SSA) isoforms. 29 sera react with RBC
60 kD Ro (SSA), 28 with Ly 60 kD Ro (SSA), 20 with RBC 54 kD Ro (SSA) and
16 with Ly 52 kD Ro (SSA). Since 15 of 16 sera reactive with Ly 52 kD Ro (SSA)
also react with RBC 54 kD Ro (SSA), we postulate that these two molecules are
structurally and antigenically related. Similarly 14 sera reacted only with the RBC
and Ly 60 kD Ro (SSA) molecules suggesting an antigenic and structural relation-
ship between them. Affinity isolation of antibodies to the various isoforms con-
firmed the antigenic relationship of the RBC and lymphocyte 60 kD forms of
Ro (SSA) and similarly the antigenic relationship of the RBC 54 kD and lym-
phocyte 52 kD forms. Finally, this heterogeneity of Ro (SSA) is relevant to the an-
ti-Ro (SSA) response as SLE sera with-Ro(SSA) and anti-nRNP all react better
with RBC 60 kD Ro (SSA) than the RBC 54 kD Ro (SSA) in Western blot. Con-
versely, SLE sera with anti-Ro (SSA) and anti-La(SSB) precipitions react preferen-
tially with RBC 54 kD Ro (SSA) over RBC 60 kD Ro (SSA) in Western blot in 90%
of instances. These differences in antigenic fine specificity are being correlated
with clinical phenomena.
Reference
1. Krapf, F. E., Herrmann, M., Leitmann, W., Kalden, J. R.: Clin. Exp. Immunol, (in
press)
Heterogeneity of the Ro(SSA) Antigen and the Autoanti-Ro (SSA)
Response: Evidence for 4 Antigenically Distinct Forms
M. Reichlin and Y. Itoh
University of Oklahoma Health Sciences Center, Oklahoma Medical Research
Foundation, Oklahoma City, OK 73104, USA
Precipitating antibodies to the Ro (SSA) antigen occur in 40% of systemic
lupus erythematosus (SLE) patients and 40-70% of patients with primary
Sjogren’s Syndrome. Previous work has shown that lymphocytes contain
2 Ro (SSA) antigens with protein moieties of 60 kD and 52 kD M.W. (J. Exp.
Med. 167, 1560- 1571, 1988). We have reported that red cells contain 2 analogous
but antigenically distinct Ro (SSA) molecules of M. W. 60 kD and 54 kD (J. Clin.
Invest. 83, 1293-1298, 1989). Of 43 sera with precipitating anti-Ro(SSA), some
bind only one of the 4 isoforms in Western blot analysis. Moreover 42 of the 43
anti-Ro (SSA) bind 1 or more of the 4 Ro (SSA) isoforms. 29 sera react with RBC
60 kD Ro (SSA), 28 with Ly 60 kD Ro (SSA), 20 with RBC 54 kD Ro (SSA) and
16 with Ly 52 kD Ro (SSA). Since 15 of 16 sera reactive with Ly 52 kD Ro (SSA)
also react with RBC 54 kD Ro (SSA), we postulate that these two molecules are
structurally and antigenically related. Similarly 14 sera reacted only with the RBC
and Ly 60 kD Ro (SSA) molecules suggesting an antigenic and structural relation-
ship between them. Affinity isolation of antibodies to the various isoforms con-
firmed the antigenic relationship of the RBC and lymphocyte 60 kD forms of
Ro (SSA) and similarly the antigenic relationship of the RBC 54 kD and lym-
phocyte 52 kD forms. Finally, this heterogeneity of Ro (SSA) is relevant to the an-
ti-Ro (SSA) response as SLE sera with-Ro(SSA) and anti-nRNP all react better
with RBC 60 kD Ro (SSA) than the RBC 54 kD Ro (SSA) in Western blot. Con-
versely, SLE sera with anti-Ro (SSA) and anti-La(SSB) precipitions react preferen-
tially with RBC 54 kD Ro (SSA) over RBC 60 kD Ro (SSA) in Western blot in 90%
of instances. These differences in antigenic fine specificity are being correlated
with clinical phenomena.