Immune reconstitution inflammatory syndrome in HIV infection: taking the bad with the good

In this review, we will describe the immunopathogies of immune reconstitution inflammatory syndrome, IRIS. IRIS occurs in a small subset of HIV patient, initiating combination antiretroviral therapy (ART), where immune reconstitution becomes dysregulated, resulting in an overly robust antigen‐specific inflammatory reaction. We will discuss IRIS in terms of the associated coinfections: mycobacteria, cryptococci, and viruses.     

The nature of the lymphopenic environment dictates protective function of homeostatic-memory CD8+ T cells

A functional memory T cell pool is critical for resistance to pathogen reinfection. Lymphopenia produces memory-like CD8⁺ T cells through homeostatic proliferation, and such “HP-memory” cells can control lethal bacterial infections similarly to conventional, antigen-experienced, memory T cells. These 2 pathways for memory T cell generation are quite distinct. We show here, however, that similar factors are required for production of protective memory CD8 T cells via both homeostatic and conventional pathways. Induction of protective HP-memory CD8 T cells requires CD4⁺ T cell “help,” which we show is antigen nonspecific yet requires CD40L–CD40 interactions with host cells. The functional competence of HP-memory CD8 T cells also requires release of endogenous bacterial components (which follows irradiation-induced lymphopenia), potentially mimicking the role of adjuvants in conventional immune responses. Lymphopenic environments lacking these key factors support similar CD8 T cell homeostatic proliferation and the acquisition of memory phenotype, yet the HP-memory cells generated are defective in pathogen elimination. These findings suggest unexpected parallels in the requirements for generating protective memory CD8 T cells by distinct pathways, and they suggest ways to bolster immune competence during recovery from lymphopenia.     

B-cell activating factor receptor deficiency is associated with an adult-onset antibody deficiency syndrome in humans

B-cell survival depends on signals induced by B-cell activating factor (BAFF) binding to its receptor (BAFF-R). In mice, mutations in BAFF or BAFF-R cause B-cell lymphopenia and antibody deficiency. Analyzing BAFF-R expression and BAFF-binding to B cells in common variable immunodeficiency (CVID) patients, we identified two siblings carrying a homozygous deletion in the BAFF-R gene. Removing most of the BAFF-R transmembrane part, the deletion precludes BAFF-R expression. Without BAFF-R, B-cell development is arrested at the stage of transitional B cells and the numbers of all subsequent B-cell stages are severely reduced. Both siblings have lower IgG and IgM serum levels but, unlike most CVID patients, normal IgA concentrations. They also did not mount a T-independent immune response against pneumococcal cell wall polysaccharides but only one BAFF-R-deficient sibling developed recurrent infections. Therefore, deletion of the BAFF-R gene in humans causes a characteristic immunological phenotype but it does not necessarily lead to a clinically manifest immunodeficiency.     

The early immunological response to acute ischemic stroke: Differential gene expression in subpopulations of mononuclear cells

Peripheral blood mononuclear cells (PBMCs), i.e. lymphocytes, monocytes and macrophages are key players in the development of innate and adaptive immune responses. However, little is known about their properties in patients with acute stroke. Experimental procedures: We presently characterized the early time course of PBMC subpopulations in 19 patients with acute ischemic stroke and symptom onset below 6 h compared to 19 age-matched healthy subjects. Immediately after acute ischemic stroke, as well as 1 and 3 days thereafter, PBMC subpopulations (cluster of differentiation [CD]3+, CD14+, CD19+, CD68+) were isolated by magnetic bead system and the expression of proinflammatory (CD40, tumor necrosis factor-alpha [TNFα]), proapoptotic (caspase-3 [CPP32], poly(ADP-ribose) polymerase [PARP]) and adhesion relevant (CD38) genes was measured by quantitative polymerase chain reaction (PCR). Furthermore, besides routine parameters, plasma levels of oxidized low-density lipoproteins (oxLDL) were studied. Results: In comparison to healthy subjects, patients revealed (i) twofold elevated plasma oxLDL concentrations, (ii) decreased (15%) blood cholesterol levels, and (iii) a 40% decrease in total number of lymphocytes. Furthermore, the majority of PBMC subpopulations revealed an increased expression of proinflammatory, proapoptotic or adhesion-relevant genes. Significant positive correlations were observed between expression of most of these genes in PBMCs and individual plasma oxLDL concentrations. Conclusion: Elevated expression of proinflammatory, proapoptotic and adhesion genes in subsets of PBMCs after ischemic stroke may contribute to an immunodepressive syndrome, possibly due to increased plasma oxLDL levels.     

The effect of intranasal and inhaled corticosteroids in healthy volunteers on the number of circulating lymphocytes and lymphocyte subsets

BACKGROUND: There has been an increasing interest in the potential systemic effects of inhaled corticosteroids. METHODS: The effect of locally inhaled corticosteroids in the nose and lung on blood lymphocytes was measured in two studies. In the first study, budesonide (BUD) (200 and 800 microg), fluticasone propionate (FP) (200 and 800 microg), and placebo were administered in the nose, and BUD (1600 microg) and FP (1500 microg) were inhaled into the lungs in a blinded, randomized fashion by 12 healthy volunteers. Blood samples were taken before and 4 h after the administration of the drug, and total lymphocyte count and different subpopulations were determined. In the second study, 15 healthy volunteers were randomized to BUD (1600 microg), FP (1600 microg), or placebo inhaled into the lungs. Blood samples were taken before and 4, 8, 24, 48, and 148 h (=7 days) after inhalation of the medication. RESULTS: Neither the nasal applications nor the inhalation of FP (1500 microg/1600 microg) showed significant differences in total lymphocyte count or different subpopulations between baseline and 4 h after the administration. In both studies, a significant reduction was found in the total lymphocyte count, B cells, T cells, and the CD4+ and the CD8+ fractions 4 h after application of BUD 1600 microg. CONCLUSIONS: Nasal application of BUD or FP in doses up to 800 microg do not induce lymphopenia. BUD 1600 microg inhalation in the lung reduces lymphocytes and their subfractions. Further studies have to be done to determine whether the results obtained in this study in healthy volunteers will also be found in patients with diseased mucosa and whether there is any correlation with adverse effects such as growth inhibition or osteoporosis.     

A reduction in the number of peripheral CD28+CD8+T cells in the acute phase of influenza

Influenza patients show a high incidence of T lymphocytopenia in the acute phase of the illness. Since CD8+ T cells play an important role in influenza virus infection, we investigated which subset of CD8+ T cells was involved in this lymphocytopenia. CD8+ T cells from eight patients with influenza A were studied for lymphocyte count, surface marker, and intracellular IFN-gamma production in the acute (days 1-3) and recovery phases (days 9-12). Total and T lymphocyte counts in the acute phase were approximately three times less than in the recovery phase; however, the CD4/8 ratio was the same in both phases. The cell count reduction in the acute phase was attributed predominantly to the CD28+ CD8+ subset, compared with the CD28- CD8+ subset. The memory/activation marker CD45RO on the CD8+ T cells was assessed. The CD28+ CD45RO- subset, a naive phenotype, was reduced significantly in number in the acute phase compared with the recovery phase. The CD28+ CD45RO+ subset, a memory phenotype, was also reduced in the acute phase, but the reduction was not statistically significant. Intracellular IFN-gamma in the CD8+ subset after mitogenic stimulation was measured by flow cytometry; the percentage of CD28+ IFN-gamma-/CD8+ subset in the acute phase was significantly less than in the recovery phase. These results indicated that the predominant reduction of peripheral CD8+ T cells in the acute phase of influenza was from naive-type lymphocytes, suggesting that these quantitative and qualitative changes of CD8+ T cells in influenza are important for understanding the immunological pathogenesis.     

Modifications of haematological series in patients co-infected with human immunodeficiency virus and hepatitis C virus during treatment with interferon and ribavirin: differences between pegylated and standard interferon

Therapy with interferon and ribavirin for hepatitis C virus (HCV) infection induces a decrease in several haematological population counts. It is unclear whether haematological toxicity is more severe in patients co-infected with HCV and human immunodeficiency virus (HIV). This study analysed the evolution of haematological population counts during and after interferon and ribavirin therapy for chronic HCV infection. Eleven patients co-infected with HIV and HCV and treated with pegylated interferon plus ribavirin, and ten treated with standard interferon plus ribavirin, were analysed. With reference to baseline values, neutrophil counts decreased by an average of 45% (range 18-67%), total lymphocytes by 50% (16-63%), CD4 lymphocytes by 54% (16-61%), haemoglobin by 9% (5-16%) and platelets by 31% (16-45%). The nadir of the decrease was reached in the first weeks of therapy and was maintained while patients were receiving treatment. The reduction in all series was higher with pegylated interferon. Patients recovered their baseline counts after finishing the treatment. No cases of haemorrhage or outstanding infection were detected during follow-up.     

Lymphopenia in occupational pulmonary silicosis with or without autoimmune disease.

An increased prevalence of autoimmune diseases such as rheumatoid arthritis has been demonstrated in silica-exposed patients. The aim of this study was to determine the peripheral blood lymphocyte phenotype in a population of silicotic workers employed in the slate mines of the district. Silicosis was assessed in 58 patients according to the International Labor Office's criteria. Clinical and biological data including flow cytometric evaluation of the lymphocyte subsets were compared with those from 41 healthy volunteers. The silicotic patients had a higher prevalence of autoimmune diseases (6/58 versus 0/41: P < 0.05) and of elevated antinuclear antibody titres compared to the control group. A very significant decrease of total lymphocyte count (P < 0.001) involving B, T and Natural Killer cells was found in silicotic patients as compared with matched healthy volunteers. A significant increase in the percentage of activated T cells (12.3%) was observed in the silicotic group as compared to 6.5% in the control group (P = 5 x 10(-5)). Our results show that in silicotic patients, the absolute number of circulating lymphocytes is diminished with an increased proportion of activated T cells. Whether these findings could predispose to the development of autoimmune disorders is discussed.