Three independent mutations involving the apoptosis-1 (APO-1)/Fas receptor or its putative ligand have led to lupuslike diseases associated with lymphadenopathy in different strains of mice. To determine whether humans with SLE also have a defect in this apoptosis pathway, we analyzed the expression of APO-1 on freshly isolated blood mononuclear cells and on lymphocytes activated in vitro using flow cytometry and the monoclonal antibody anti-APO-1. Significantly higher levels of APO-1 expression were detected on freshly isolated peripheral B cells and both CD4' and CD8' T lymphocyte populations obtained from lupus patients when compared with normal controls (P < 0.001). Almost 90% of the cells that stained positive for APO-1 also expressed the CD29 antigen, suggesting that APO-1 was upregulated after lymphocyte activation in vivo. No defect in APO-1 regulation was detected after activation of SLE T (with anti-CD3) or B (with Staphylococcus aureus Cowan 1) lymphocytes in the presence of IL-2 in vitro. Similarly, the anti-APO-1 antibody induced apoptosis in 74±5% of activated SLE T cells in vitro compared with 79±6% of the normal controls (P > 0.05). These results reveal that, while APO-1 / Fas may play an important role in the regulation of lymphocyte survival in SLE, no consistent defect in the expression or function of the receptor could be detected in these studies. (J. Clin.

Autoantibodies to a polymerase III transcription factor, La (SS-B), are frequently detected in the serum of patients with Sjogren's syndrome and systemic lupus erythematosus. To define the humoral immune response to this protein, we analyzed the patterns of antibody recognition toward 13 recombinant La peptides by immunoblotting and determined the heterogeneity of antibodies reactive with the immunodominant epitopes. The smallest epitopes that were strongly antigenic and recognized by > 70% of sera tested (immunodominant) were encoded by the subclones BgX and XA located in the 5' and 3' halves of the La cDNA, respectively. Conformation of the immunodominant La peptides played a major role in antibody recognition. Although greater diversity in antibody binding to carboxyl-terminal La peptides was observed, the overall pattern of peptide recognition by anti-La antibodies was similar in different diseases. The antibody responses to the immunodominant peptides were strongly correlated (r = 0.68, P < 0.001). One-and two-dimensional isoelectric focusing of affinity purified IgG anti-La peptide antibodies revealed restricted heterogeneity and oligoclonal bands (K light chains). These observations suggest that anti-La antibodies are induced and/or maintained by the self antigen and that their diversity is constrained either by mechanisms related to tolerance or by affinity maturation of the humoral immune response. (J. Clin. Invest. 1990. 85:325-333.) autoantibody -epitope mapping * La (SS-B) * systemic lupus erythematosus

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SUMMARYThis study was undertaken to determine the role of antibodies against both recombinant Ro (r-Ro) and La (r-La) proteins and polypeptides derived from the recombinant La protein in predicting fetal and neonatal outcome in children at risk to develop neonatal lupus erythematosus (NLE). All sera were obtained in the perinatal period and quantitative ELISA assays were used. We collected 41 maternal sera within 2 months of delivery ofa child with NLE (21 with congenital heart disease block (CHB) and 20 with dermalologic NLE) and 19 sera from anti-Ro and/or anti-La antibodypositive mothers with systemic lupus erythematosus (SLE) who delivered a child without NLE. All sera were tested for anti-r-La aod anti-r-Ro antibodies by ELISA, and most sera were tested for antibodies directed against La polypeptides by immunoblot. We found significantly higher anti-rLa antibody levels in the sera from mothers of children with NLE compared with sera from mothers of unaffected children (067 i 0-43 versus 0-14 ± 0-30: P < 0 0001). There was a statistically significant difference in the mean anti-r-La levels between the sera of mothers of children with CHB compared with dermatologic NLE (0-51 ±0 45 versus 083 ±0 37 respectively; /'^O 0091). When we examined antibodies directed against the recombinant 52-kD Ro protein, there was a statistically significant elevation of titres in the sera of mothers of NLE children (0 77±0 35) compared with non-NLE mothers (0'29±0 39; /*