Validation of the ALS assay in adult patients with culture confirmed pulmonary tuberculosis.

BACKGROUND: We have earlier shown that Bacille Calmette-Guérin (BCG) vaccine-specific IgG Antibodies in Lymphocyte Supernatant (ALS) can be used for diagnosis of active tuberculosis (TB) in adults and children. METHODOLOGY/PRINCIPAL FINDINGS: The ALS method was validated in a larger cohort (n = 212) of patients with suspicion of pulmonary TB using multiple antigens (BCG, LAM, TB15.3, TB51A, CFP10-ESAT6-A, CFP, CW) from Mycobacterium tuberculosis. The sensitivity and specificity of the ALS assay was calculated using non-TB patients as controls. The sensitivity and the specificity were highest with BCG vaccine (90% and 88% respectively) followed by LAM (89% and 87% respectively). Simultaneous assessment of multiple antigen-specific antibodies increased sensitivity (91%) and specificity (88%). Using higher lymphocyte count in smaller volume of culture media increased detection and reduced the assay duration to ∼30 hrs. Twenty one patients with clinical findings strongly suggestive of TB finally diagnosed as non-TB patients were positive by the ALS assay, of which 9 (43%) were positive for 7 antigens and 19 (90%) for at least 3 antigens. CONCLUSIONS/SIGNIFICANCE: Our findings show that simultaneous detection of antigens improves the diagnostic potential of the ALS assay; the modified method increases sensitivity and can provide results in <48 hours, and enable detection of some cases of pulmonary TB that are not detectable by standard methods.

Low birth weight is associated with altered immune function in rural Bangladeshi children: a birth cohort study.

BACKGROUND: Low birth weight is generally an outcome of a fetal insult or nutritional insufficiency. Recent studies have shown that such exposure early in life may have long-term implications for later immunocompetence and susceptibility to infectious diseases. OBJECTIVE: We aimed to investigate the effect of birth weight on immune function in preschool-age children. DESIGN: A birth cohort cross-sectional study was conducted in children (n = 132) aged 60.8 +/- 0.32 mo who were born in Matlab, a rural area of Bangladesh, and whose weight and length were measured within 72 h of birth. The outcome measures were thymopoiesis, T cell turnover, acute phase response, and percentage of lymphocytes. RESULTS: Children born with low birth weight (<2500 g; LBW group, n = 66) had significantly higher concentrations of T cell receptor excision circles in peripheral blood mononuclear cells-a biomarker for thymopoiesis-and significantly higher serum bactericidal activity and C-reactive protein concentrations than did children born with normal birth weight (>or=2500 g; NBW group, n = 66) (P < 0.05 for both). The LBW group children had significantly lower concentrations of interleukin 7 in plasma (P = 0.02), shorter telomere length in peripheral blood mononuclear cells (P = 0.02), and a lower percentage of CD3 T cells (P = 0.06) than did the NBW group children. CONCLUSIONS: Greater peripheral T cell turnover (shorter telomeres and lower CD3 concentrations) due to immune activation (elevated C-reactive protein concentrations and bactericidal activity) may have resulted in a greater need for replenishment from the thymus (higher T cell receptor excision circles); these events may cause lower immune functional reserve in preschool-age children born with LBW. Thus, LBW has implications for immunocompetence and increased vulnerability to infectious diseases in later life.

Improved outcome in shigellosis associated with butyrate induction of an endogenous peptide antibiotic.

Shigella is a major cause of morbidity, mortality, and growth retardation for children in developing countries. Emergence of antibiotic resistance among Shigellae demands the development of effective medicines. Previous studies found that the endogenous antimicrobial peptide LL-37 is down-regulated in the rectal epithelium of patients during shigellosis and that butyrate up-regulates the expression of LL-37 in colonic epithelial cells in vitro and decreases severity of inflammation in experimental shigellosis. In this study, Shigella-infected dysenteric rabbits were treated with butyrate (0.14 mmol/kg of body weight) twice daily for 3 days, and the expression levels of the rabbit homologue to LL-37, CAP-18, were monitored in the colon. Butyrate treatment resulted in (i) reduced clinical illness, severity of inflammation in the colon, and bacterial load in the stool, (ii) significant up-regulation of CAP-18 in the surface epithelium, and (iii) disappearance of CAP-18-positive cells in lamina propria. The active CAP-18 peptide was released in stool from its proform by butyrate treatment. In healthy controls, CAP-18 expression was localized predominantly to the epithelial surface of the colon. In infected rabbits, CAP-18 expression was localized to immune and inflammatory cells in the colon, whereas the ulcerated epithelium was devoid of CAP-18 expression. The combination of CAP-18 and butyrate was more efficient in killing Shigella in vitro than CAP-18 alone. Our findings indicate that oral butyrate treatment in shigellosis may be of clinical value because of induction of the endogenous cathelicidin CAP-18 in the colonic epithelium, stimulation of the release of the active peptide CAP-18, and promoting elimination of Shigella.

Use of antibodies in lymphocyte secretions for detection of subclinical tuberculosis infection in asymptomatic contacts.

We have previously demonstrated that Mycobacterium bovis BCG-specific immunoglobulin G antibodies in lymphocyte secretions (ALS) can be employed as a marker for active tuberculosis (TB). We aimed to determine whether the ALS method allows detection of subclinical TB infection in asymptomatic individuals. A prospective study of family contacts (FCs) of patients with active TB and healthy controls was performed. Thirteen of 42 FCs had high ALS responses, including 6 FCs who subsequently developed active TB. No correlation was observed between the tuberculin skin test and the ALS responses in the FCs (r = 0.1, P = 0.23). Among patients with active TB, BCG-specific ALS responses steadily declined from the time of diagnosis through 6 months following antimycobacterial chemotherapy (P = 0.001). The ALS assay enabled detection of infection in exposed symptom-free contacts, who are at greater risk for developing active TB. The method may also allow discrimination between effective treatment of active infection and suboptimal response to therapy.