Sjögren’s syndrome (SjS) patients often have a variety of extraglandular manifestations including neurological and gastrointestinal involvement. In this study we evaluated the diagnostic performance of luciferase immunoprecipitation system (LIPS) that employs mammalian cell-produced recombinant antigens for analyzing SjS autoantibody responses. LIPS testing of mammalian cell-produced La, Ro60 and Ro52 recombinant antigens with defined commercial antibodies demonstrated highly specific immunoprecitation of each antigen without cross-reactivity. Next, sera from 57 SjS and 25 volunteers were evaluated by LIPS against a panel of human autoantigens. LIPS detected robust anti-La antibody levels in 43/57 SjS patients (75% sensitivity) and markedly outperformed an ELISA (46% sensitivity). Profiling of other SjS-associated autoantigens revealed the presence of anti-Ro60, anti-Ro52 in 63% and 61%, of SjS patients, respectively. Interestingly, a C-terminal fragment of Ro52 (Ro52-Δ2), a protein fragment not previously found to be antigenic by ELISA, also showed positive immunoreactivity in 42/57 SjS patients (65% sensitivity). Additional profiling of other autoantigens revealed that certain SjS patients also showed positive immunoreactivity with thyroid peroxidase (14%), AQP-4 (12%) and the H+/K+ gastric ATPase (16%) suggesting potential autoantibody attack of thyroid, neuronal and gastric parietal cells, respectively. These heterogeneous autoantibody responses detected by LIPS in SjS will likely be useful for diagnosis and for evaluating extraglandular manifestations.

Antibody responses against lytic and latent KSHV antigens were investigated in patients with Kaposi sarcoma (KS), multicentric Castleman’s disease (MCD), and primary effusion lymphoma. Antibodies against the lytic antigen K8.1 were 5-fold higher in MCD than KS patients, while antibodies to the sum of latent antigens v-cyclin and LANA were 27-fold higher in KS compared to MCD patients (P< 0.0001). The sum of anti-v-cyclin and anti-LANA antibody titers discriminated patients with KS from those with MCD and KS with 93% sensitivity and 83% specificity. These results suggest that antibody responses to lytic and latent KSHV antigens differ in these diseases.

There is currently a need for improved serological tests for the diagnosis and monitoring of Lyme disease, an infection caused by Borrelia burgdorferi. In the present study, we evaluated luciferase immunoprecipitation systems (LIPSs) for use for profiling of the antibody responses to a panel of B. burgdorferi proteins for the diagnosis of Lyme disease. Initially, serum samples from a cohort of patients and controls (n ‫؍‬ 46) were used for training and were profiled by the use of 15 different B. burgdorferi antigen constructs. For the patient sera, the antibody responses to several B. burgdorferi antigens, including VlsE, flagellin (FlaB), BmpA, DbpA, and DbpB, indicated that the antigens had high levels of immunoreactivity. However, the best diagnostic performance was achieved with a synthetic protein, designated VOVO, consisting of a repeated antigenic peptide sequence, VlsE-OspC-VlsE-OspC, Analysis of an independent set of serum samples (n ‫؍‬ 139) used for validation showed that the VOVO LIPS test had 98% sensitivity (95% confidence interval [CI], 93% to 100%; P < 0.0001) and 100% specificity (95% CI, 94% to 100%; P < 0.0001). Similarly, the C6 peptide enzyme-linked immunosorbent assay (ELISA) also had 98% sensitivity (95% CI, 93% to 100%; P < 0.0001) and 98% specificity (95% CI, 90% to 100%; P < 0.0001). Receiver operating characteristic analysis revealed that the rates of detection of Lyme disease by the LIPS test and the C6 ELISA were not statistically different. However, the VOVO LIPS test displayed a wide dynamic range of antibody detection spanning over 10,000-fold without the need for serum dilution. These results suggest that screening by the LIPS test with VOVO and other B. burgdorferi antigens offers an efficient quantitative approach for evaluation of the antibody responses in patients with Lyme disease.Lyme disease is caused by the spirochete Borrelia burgdorferi, which is transmitted by the bite of a deer tick (Ixodes sp.) (24,29). One of the first signs of B. burgdorferi infection is erythema migrans (EM), a skin lesion that appears within a few days at the site of the bite. Subsequently, the spirochetes can disseminate into the bloodstream and then to various target tissues and cause neurological, cardiac, and rheumatological complications (24, 29). Some individuals develop post-Lyme disease syndrome (PLDS) and have lingering symptoms, such as fatigue, musculoskeletal pain, and cognitive impairment (22,24,29).Currently, the Centers for Diseases Control and Prevention (CDC) recommends the use of a two-tier approach for serological testing for Lyme disease (1). The two-tier approach includes an initial enzyme immunoassay or immunofluorescence assay, followed by Western blotting for positive or borderline samples. The limitations of the two-tier testing approach include a low sensitivity in the very early stages of the B. burgdorferi infection, subjectivity in the interpretation of the Western blot bands, and the significant amount of time and the significant cost for the process. Moreover, curre...