Antigens of Mycobacterium tuberculosis Recognized by Antibodies during Incipient, Subclinical Tuberculosis

Serum samples obtained from human immunodeficiency virus (HIV)-infected tuberculosis (TB) patients months prior to clinical TB were used to delineate the profile of Mycobacterium tuberculosis culture filtrate proteins recognized during subclinical TB. A subset of ~12 antigens was recognized by antibodies in these serum samples. Antibodies to two of these antigens (81 [88]-kDa malate synthase [GlcB] and MPT51) were present in serum samples obtained during incipient subclinical TB in 19 (~90%) of the 21 HIV-infected TB patients tested. These antigens will be useful for devising diagnostic tests that can identify HIV-positive individuals who are at a high risk for developing clinical TB.     

Mechanisms of immunotherapeutic intervention by anti-CD154 (CD40L) antibody in high-risk corneal transplantation.

This study aimed to determine the effects of anti-CD154 on T cell cytokine profiles and ocular chemokine gene expression after high-risk corneal transplantation and to specifically determine if CD154 blockade is associated with a switch from a Th1 to a Th2 alloimmune response. Mice were used as recipients of syngeneic or multiple minor H or MHC antigen-mismatched corneal grafts. Recipient beds were neovascularized (high-risk). Hosts were randomized to receive either anti-CD154 antibody or control immunoglobulin (Ig) perioperatively. Two weeks after corneal transplantation, allospecific delayed-type hypersensitivity (DTH) was evaluated. Frequencies of interferon-gamma (IFN-gamma)-, interleukin-2 (IL-2)-, IL-4-, and IL-5-secreting T cells in the hosts were measured by enzyme-linked immunospot (ELISPOT) assay. Ocular chemokine gene expression in anti-CD154-treated and control hamster Ig-treated groups was determined using a multiprobe ribonuclease protection assay (RPA). Leukocyte infiltration of corneal grafts was evaluated microscopically. Anti-CD154-treated mice did not exhibit allospecific DTH. The frequencies of Th1 cytokine-producing but not Th2 cytokine-producing T cells were significantly reduced in anti-CD154-treated hosts. Postoperative mRNA levels of RANTES and macrophage inflammatory protein-1beta (MIP-1beta) in anti-CD154-treated eyes were substantially suppressed compared with hamster Ig-treated controls. Leukocyte infiltration was profoundly suppressed in grafts of anti-CD154-treated hosts. These data demonstrate that blockade of the CD40-CD154 costimulatory pathway after corneal transplantation inhibits Th1-mediated responses but does not induce a switch to a Th2-specific response. In addition, anti-CD154 therapy suppresses ocular chemokine gene expression and leukocytic infiltration into allografts.     

Exclusion of first-episode deep-vein thrombosis after-hours using D-dimer.

The objective of this study was to test the safety of withholding anticoagulant treatment and additional call-back diagnostic testing with ultrasound in patients who have a negative D-dimer at presentation. Patients with signs and symptoms of deep-vein thrombosis who presented to the emergency department after regular hours and on weekends underwent D-dimer testing using the STA-Liatest D-di. In patients with negative D-dimer results, heparin therapy was withheld, and no further diagnostic testing for deep-vein thrombosis was done as part of the initial evaluation. Patients with positive D-dimer results underwent compression ultrasonography. The primary outcome measure was a diagnosis of new symptomatic venous thromboembolism confirmed by diagnostic testing during the 3-month follow-up period. Of the 260 eligible patients, 81 (31%) had a negative D-dimer and 179 (69%) had a positive D-dimer. No patient with a negative D-dimer at presentation had confirmed venous thromboembolism at 3-month follow-up. Three patients died: one by intracranial hemorrhage secondary to cerebrovascular accident; and two deaths of indeterminate cause almost 3 months after entry. The automated assay for D-dimer, the STA-Liatest D-di, seems to provide a simple method with high clinical utility for excluding acute first-episode deep-vein thrombosis in symptomatic patients who present to the emergency room after regular hours.     

Molecular mechanisms of apoptosis in the cells of the immune system in human aging

Summary: Aging is associated with progressive decline in immune functions and increased frequency of infections, autoimmunity, and cancer. Among immune functions, a decline in T‐cell functions during aging predominates. In this review, I discuss the molecular signaling of three distinct pathways of apoptosis, namely the death receptor pathway, the mitochondrial pathway, and the most recently described endoplasmic reticulum stress pathway, and the relative sensitivity of naïve, central memory, and effector memory CD8⁺ T‐cell subsets to apoptosis. In addition, I review apoptosis, especially via death receptor pathway, in naïve and various memory subsets of CD4⁺ and CD8⁺ T cells (with primary emphasis on CD8⁺ naïve and memory subsets) in human aging and discuss the role of apoptosis in immune senescence.     

P-glycoprotein (MDR 1 gene product) in cells of the immune system: Its possible physiologic role and alteration in aging and human immunodeficiency virus-1 (HIV-1) infection

P-glycoprotein, a 170-kd glycoprotein encoded by theMDR 1 gene, is a member of a highly conserved superfamily of ATP-binding cassette (ABC) transport proteins. It shares extensive homology with numerous bacterial and eukaryotic ABC transport proteins. P-glycoprotein acts as an energy-dependent efflux pump that appears to transport structurally diverse agents ranging from ions to peptides. P-glycoprotein (P-gP) has been implicated as playing a role in multidrug (MDR) resistance in cancer, chloroquine-resistantPlasmodium falciparum infection, and possibly human immunodeficiency virus-1 (HIV-1) resistance to nucleoside compounds. A number of normal tissues in humans and rodents have been shown to express high levels of P-gp. The expression and function of P-gp in cells of the immune system have been explored in the past 2 years. This review presents a state of the art regarding the expression, regulation, and function of Pgp in cells of the immune system. In addition, its alteration in aging and HIV-1 infection is reviewed. A possible physiologic role of P-gp in cytokine secretion, antigen processing/presentation, and effector functions is also discussed.     

Correlation between Presence of Viable Bacteria and Presence of Endotoxin in Middle-Ear Effusions

The presence of endotoxin (detected by the Limulus amebocyte lysate assay) was compared to the presence of viable Haemophilus influenzae and Moraxella catarrhalis (detected by PCR) in 106 middle-ear effusions from pediatric patients with chronic otitis media. Endotoxin was found in 81 of the 106 specimens. Of these 81 specimens, 66 (81.5%) also tested positive for one or both of the gram-negative bacteria H. influenzae and M. catarrhalis. The data suggest that viable gram-negative bacteria, detectable by PCR but often undetectable by culture, may be the source of endotoxin in middle-ear effusions.     

Effects of prednisolone treatment on cytokine expression in patients with leprosy type 1 reactions

Leprosy type 1 reactions (T1R) are due to increased cell-mediated immunity and result in localized tissue damage. The anti-inflammatory drug prednisolone is used for treatment, but there is little good in vivo data on the molecular actions of prednisolone. We investigated the effect of prednisolone treatment on tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-10, and transforming growth factor beta1 (TGF-beta1) mRNA and protein expression in blood and skin biopsies from 30 patients with T1R in India. After 1 month of prednisolone treatment the sizes of the skin granulomas were reduced, as were the grades of cells positive for TNF-alpha and IL-10 in skin lesions. Increased production of TGF-beta1 was seen in skin lesions after 6 months of prednisolone treatment. Expression of mRNA for TNF-alpha, IL-1beta, and TGF-beta1 was reduced, whereas no change in IL-10 mRNA expression was detected during treatment. The circulating cytokine profiles were similar in patients with and without T1R, and prednisolone treatment had no detectable effects on cytokine expression in the blood. The data emphasize the compartmentalization of pathology in T1R and the importance of the immune response in the skin. Clinical improvement and cytokine expression were compared. Surprisingly, patients with improved skin and nerve function and patients with nonimproved skin and nerve function had similar cytokine profiles, suggesting that clinical improvement is not directly mediated by the cytokines studied here. This in vivo well-controlled study of the immunosuppressive effects of prednisolone showed that the drug does not switch off cytokine responses effectively.