Review for the generalist: The antinuclear antibody test in children - When to use it and what to do with a positive titer.

The antinuclear antibody test (ANA) is a much overused test in pediatrics. The ANA does have a role in serologic testing but it should be a very limited one. It is often ordered as a screening test for rheumatic illnesses in a primary care setting. However, since it has low specificity and sensitivity for most rheumatic and musculoskeletal illnesses in children, it should not be ordered as a screening test for non-specific complaints such as musculoskeletal pain. It should only be used as a diagnostic test for children with probable Systemic Lupus Erythematosus (SLE) or Mixed Connective Tissue Disease, (MCTD) and other possible overlap-like illnesses. Such children should have developed definite signs and symptoms of a disease before the ANA is ordered. This review presents data supporting these conclusions and a review of the ANA literature in adults and children.By limiting ANA testing, primary care providers can avoid needless venipuncture pain, unnecessary referrals, extra medical expenses, and most importantly, significant parental anxieties. It is best not to do the ANA test in most children but if it ordered and is positive in a low titer (<1:640), the results can be ignored if the child is otherwise well and does not have other features of a systemic illness.

Indications for a disturbed peripheral T-cell homeostasis in juvenile idiopathic arthritis (JIA): absent expansion of CD28 T-cells and no decrease of naive T-cells in cytomegalovirus-positive patients with JIA.

OBJECTIVE: To investigate the influence of latent cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections on CD28-expressing T-cell subpopulations and replicative senescence of naive T-cells as a marker for aging of the immune system in children with juvenile ideopathic arthritis (JIA). METHODS: T-cell subpopulations were analyzed from 24 patients with JIA and 61 healthy age-matched controls by fluorescence activated cell sorting. Relative telomere length (RTL) in CD4+CD28+CD45RA+ (naive) T-cells was measured by quantitative polymerase chain reaction. RESULTS: Although confirming known data of expansions of CD28- T-cells and tendency of decreasing naive T-cells in CMV-seropositive healthy individuals, our findings did not show a marked influence of latent EBV or CMV infection on CD28-expressing T-cells in patients with JIA. In contrast, CMV was an independent factor for loss of CD28, regardless of age, in healthy controls. Irrespective of serology results for CMV or EBV, patients with JIA showed signficantly decreased RTL compared to age-matched controls. Regression lines for RTL and age revealed decreased RTL with advancing age in CMV-positive and EBV-positive subjects. The evidence that findings for CMV-positive JIA patients did not resemble the findings of healthy CMV-positive controls, namely expansion of CD28- T-cells and decrease of naive T-cells, may support the theory of a disturbed peripheral T-cell homeostasis in JIA. CONCLUSION: Diminished mechanisms of T-cell homeostasis and premature aging of the immune system may play a role in the pathogenesis of JIA.