Assessment of in vivo frequency of mutated T cells in patients with systemic lupus erythematosus.

The frequency of mutant T cells (FMC) in blood lymphocytes from patients with systemic lupus erythematosus (SLE) was measured by growing cells in the presence and in the absence of 6-thioguanine. Patients with SLE had a spectrum of FMC ranging from normal to about 100 times normal. This high FMC among cells from SLE patients appears to reflect excessive in vivo activation and proliferation during the course of the disease. This represents the first demonstration of such a T cell abnormality in SLE; it supports the hypothesis that SLE T cells demonstrate increased in vivo division and/or survival.

Age alters ADPase positive dendritic (Langerhans) cell response to P. aeruginosa ocular challenge.

The morphology, distribution and quantitation of dendritic (Langerhans) cells (LC) was determined by analysis of ADPase stained epithelial flat mounts from 6-8 week young adult (resistant) and 24 month old (susceptible) aged mice before and after experimental infection with P. aeruginosa topically applied to the scarified cornea. The contralateral eye (controls) was also scarified and phosphate buffered saline applied similarly. This study has examined the changes in ADPase positive cell populations of the conjunctival limbal epithelium and corneal epithelium of naturally resistant mice (Swiss-Webster and CD2F1) following corneal infection with Pseudomonas aeruginosa at two different ages, young adult (8 week old) and aged (24 month old). The young adult mice recover from their infection and restore corneal clarity while the aged mice have extensive ocular destruction and corneal scarring. Conjunctival limbal dendritic cell numbers in young adult mice were found to be significantly increased at day seven post infection and then returned to baseline levels. In contrast, conjunctival limbal dendritic cell numbers in aged mice were found to increase slowly and to peak at fourteen days after infection. Other differences between the two ages (young adult and aged) included an initial increase in dendritic cells five hours post infection in the young adult groups and an initial decrease at five hours in the aged groups of mice.

Characteristics of HPRT-mutant T cell lines in a lupus patient treated with cyclophosphamide.

This report describes T cell lines derived from a patient with subacute cutaneous lupus after treatment with intravenous pulse cyclophosphamide. We selected for mitotically active, hypoxanthine-guanine phosphoribosyltransferase-deficient (HPRT-) T cells, by culture in a selective medium containing 6-thioguanine. When HPRT- cell lines were derived 6 days after pulse cyclophosphamide (CYC) treatment, they were predominantly CD8+ and T cell receptor (TCR) gamma/delta+, producing interferon-gamma (IFN gamma). Cell lines derived 21 days after CYC treatment were CD4+, TCR alpha/beta+ and produced both IFN gamma and interleukin-4. These results support a possible role for gamma/delta+ T cells in subacute cutaneous lupus and suggest a mechanism for the therapeutic effect of CYC.

Assessment of clinical parameters associated with increased frequency of mutant T cells in patients with systemic lupus erythematosus.

OBJECTIVE: To determine the clinical features that contribute to an increased frequency of mutant T cells (FMC) in patients with systemic lupus erythematosus (SLE). METHODS: During in vivo T cell division, there are errors in replication which give rise to mutations throughout the genome. An estimate of such mutations may be obtained by focusing on mutations in the hprt gene, which can be screened by assessing relative growth of T cell clones in the presence and absence of 6-thioguanine. In this study, peripheral blood T cell clones from 47 patients with SLE were assessed, and the frequency of mutant T cells (FMC) determined. An attempt was made to correlate the FMC with disease measures. RESULTS: Patients with SLE had a spectrum of FMC values, ranging from normal to almost 1,000 times normal. Total duration of active disease (rs = 0.94), past highest disease activity index (rs = 0.80), and number of lupus flares (rs = 0.76) correlated most strongly (P < 0.0001) with FMC by Spearman's rank order analysis. In contrast, current disease activity index and current anti-DNA level did not correlate with FMC. Similar correlations between FMC and cumulative past lupus disease activity were found by linear regression analysis (rp = 0.89 for the correlation between the natural logarithm of FMC and cumulative duration of active disease). By both statistical tests, therapy was found to be only a minor contributor to FMC. CONCLUSION: In our patient population, a high FMC value appears to reflect cumulative clinical lupus disease activity, involving both intensity and duration of past active disease.

Outpatient monthly oral bolus cyclophosphamide therapy in systemic lupus erythematosus.

OBJECTIVE: An open label study to determine the feasibility and acute toxicity of a 6 month course of outpatient intermittent bolus high dose oral cyclophosphamide in patients with active systemic lupus erythematosus (SLE). METHODS: Oral cyclophosphamide in a single dose of 0.5 to 1.0 g/m2 was given monthly for 6 consecutive months. Disease activity was monitored by quantitative assessments of urine sediment, 24h urine protein excretion, and the Systemic Lupus Activity Measure (SLAM). RESULTS: Twelve patients (11 with glomerulonephritis and one with thrombocytopenia) were studied. Improvements in SLAM scores, proteinuria, and urinary cellular casts were observed in the majority of the 9 patients with nephritis who completed the study. Adverse effects included mild nausea in most patients and intercurrent infections in 2 patients (herpes zoster, cellulitis, urinary tract infection). Three patients failed to complete the 6 month course of therapy because of treatment failure in the patient with thrombocytopenia, pregnancy, and severe vomiting, respectively. CONCLUSION: High dose pulse oral cyclophosphamide is an acceptable alternative for the aggressive outpatient management of selected patients with lupus nephritis.