Defective immune response to Epstein-Barr virus in patients with acute lymphocytic leukemia

Serological Assessment of 18 Pathogens and Risk of AIDS-Associated Non-Hodgkin Lymphoma

BACKGROUND

HIV infection is associated with increased susceptibility to common pathogens, which may trigger chronic antigenic stimulation and hyperactivation of B cells, events known to precede the development of AIDS-associated non-Hodgkin lymphoma (AIDS-NHL).

METHODS

To explore whether cumulative exposure to infectious agents contributes to AIDS-NHL risk, we tested sera from 199 AIDS-NHL patients (pre-NHL, average lead time 3.9 years) and 199 matched HIV-infected controls from the Multicenter AIDS Cohort Study, for anti-IgG responses to 18 pathogens using multiplex serology. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression models.

RESULTS

We found no association between cumulative exposure to infectious agents and AIDS-NHL risk (OR 1.01, 95% CI: 0.91 to 1.12). However, seropositivity for trichodysplasia spinulosa polyomavirus (TSPyV), defined as presence of antibodies to TSPyV capsid protein VP1, was significantly associated with a 1.6-fold increase in AIDS-NHL risk (OR 1.62, 95% CI: 1.02 to 2.57). High Epstein-Barr virus (EBV) anti-VCA p18 antibody levels closer to the time of AIDS-NHL diagnosis (<4 years) were associated with a 2.6-fold increase in AIDS-NHL risk (OR 2.59, 95% CI: 1.17 to 5.74). In addition, high EBV anti-EBNA-1 and anti-ZEBRA antibody levels were associated with 2.1-fold (OR 0.47, 95% CI: 0.26 to 0.85) and 1.6-fold (OR 0.57, 95% CI: 0.35 to 0.93) decreased risk of AIDS-NHL, respectively.

CONCLUSIONS

Our results do not support the hypothesis that cumulative exposure to infectious agents contributes to AIDS-NHL development. However, the observed associations with respect to TSPyV seropositivity and EBV antigen antibody levels offer additional insights into the pathogenesis of AIDS-NHL.

[Chronic active Epstein-Barr virus infection]

The ubiquitous Epstein-Barr virus (EBV), which establishes latency after primary infection, does not cause any symptomatic diseases as long as cellular immunity is intact. In apparently immunocompetent individuals, a chronic infection can develop, and this has been called as chronic active EBV infection (CAEBV). CAEBV is characterized by chronic or recurrent infectious mononucleosis-like symptoms, such as fever, extensive lymphadenopathy, and, hepatosplenomegaly. This disease is rare but severe with high morbidity and mortality. Recently, its pathophysiology is not an infection but a clonal expansion of EBV-infected T or natural killer NK cells. In this review, I discuss our current understanding of the pathogenesis of CAEBV and summarize its clinical features, therapies, and prognosis.

Defective natural killer cell activity and deficient production of interferon-gamma in children with acute lymphoblastic leukemia

Natural killer (NK) cell activity, OK-432-augmented-NK cell activity, concentrations of interferon-gamma (IFN-gamma) in the culture supernatants of lymphocytes stimulated with OK-432, and subsets of NK cells and memory T cells were analyzed in 42 children with acute lymphoblastic leukemia (ALL) receiving maintenance chemotherapy. Natural killer and augmented-NK cell activities, and concentrations of IFN-gamma in the supernatants of cultured lymphocytes, were significantly lower in the patients with ALL than in age-matched control children. Among the NK cell subsets, proportions of CD57+ cells in the patients with ALL were significantly higher than in the controls, and proportions of a memory T cell subset (CD4+ CD29+ T cells) in the patients were also significantly higher than in the controls. These results suggest that the function of NK cells and memory T cells that are considered as IFN-gamma producing cells, may be defective in ALL, and that CD57+ cells and CD4+ CD29+ cells may be resistant to or recover rapidly from suppression by cytotoxic chemotherapy.

IgG subclass imbalance in children with acute lymphoblastic leukemia receiving maintenance chemotherapy

Serum levels of IgG subclasses were measured in 18 children with acute lymphoblastic leukemia (ALL) receiving maintenance chemotherapy and in 36 age-matched controls in order to attempt to analyse the effects of chemotherapy. The IgG subclasses were measured by enzyme linked immunosorbent assay. Serum IgG1, IgG2 and IgG4 levels in the patients were significantly (p less than 0.01, p less than 0.005, p less than 0.005) lower than in the controls, but serum IgG3 levels in patients were as high as in controls. Suppression on IgG2 and IgG4 were more profound than IgG1. In six children, the levels of the IgG subclasses were measured at diagnosis, during maintenance chemotherapy and one year after cessation of chemotherapy. The levels of the four IgG subclasses at diagnosis and after cessation of chemotherapy were as high as those in control children except for the IgG4 levels in the post-chemotherapy group. IgG2 and IgG4 may be more susceptible to suppression by chemotherapy than IgG1 and IgG3 may not be suppressed by chemotherapy.