The chronic Epstein-Barr virus syndrome is a poorly defined symptom complex characterized primarily by chronic or recurrent debilitating fatigue and various combinations of other symptoms, including sore throat, lymph node pain and tenderness, headache, myalgia, and arthralgias. Although the syndrome has received recent attention, and has been diagnosed in many patients, the chronic Epstein-Barr virus syndrome has not been defined consistently. Despite the name of the syndrome, both the diagnostic value of Epstein-Barr virus serologic tests and the proposed causal relationship between Epstein-Barr virus infection and patients who have been diagnosed with the chronic Epstein-Barr virus syndrome remain doubtful. We propose a new name for the chronic Epstein-Barr virus syndrome--the chronic fatigue syndrome--that more accurately describes this symptom complex as a syndrome of unknown cause characterized primarily by chronic fatigue. We also present a working definition for the chronic fatigue syndrome designed to improve the comparability and reproducibility of clinical research and epidemiologic studies, and to provide a rational basis for evaluating patients who have chronic fatigue of undetermined cause.

Interleukin 7 (IL-7) is a common gamma chain receptor cytokine implicated in thymopoiesis and in peripheral expansion and survival of T lymphocytes. The safety and activity of recombinant human IL-7 (rhIL-7) administration were therefore examined in HIV-infected persons. In this prospective randomized placebo-controlled study, a single subcutaneous dose of rhIL-7 was well tolerated with biologic activity demonstrable at 3 μg/kg and a maximum tolerated dose of 30 μg/kg. Injection site reactions and transient elevations of liver function tests were the most notable side effects. Transient increases in plasma HIV-RNA levels were observed in 6 of 11 IL-7–treated patients. Recombinant hIL-7 induced CD4 and CD8 T cells to enter cell cycle; cell-cycle entry was also confirmed in antigen-specific CD8 T cells. Administration of rhIL-7 led to transient down-regulation of the IL-7 receptor alpha chain (CD127) in both CD4+ and CD8+ T cells. Single-dose rhIL-7 increased the numbers of circulating CD4+ and CD8+ T cells, predominantly of central memory phenotype. The frequency of CD4+ T cells with a regulatory T-cell phenotype (CD25high CD127low) did not change after rhIL-7 administration. Thus, rhIL-7 has a biologic and toxicity profile suggesting a potential for therapeutic trials in HIV infection and other settings of lymphopenia. This clinical trial has been registered at http://www.clinicaltrials.gov under NCT0099671.

We investigated the cellular tropism of human B-lymphotropic virus (HBLV) (also designated Human Herpesvirus-6) in vitro by infecting fresh MN cells from normal human adult peripheral blood, umbilical cord blood, bone marrow, tonsil, and thymus. Cultures from all the sources examined contained infectable cells, as shown by the appearance of characteristic enlarged, round-shaped, short-lived cells expressing HBLV-specific markers. Detailed immunological analysis demonstrated that the vast majority of these cells expressed T cell-associated antigens (i.e., CD7, CD5, CD2, CD4, and to a lesser extent, CD8). The CD3 antigen and the TCR-alpha/beta heterodimer were not detectable on the surface membrane, but were identified within the cytoplasm of HBLV-infected cells, by both immunofluorescence and radioimmunoprecipitation assay. A proportion of the HBLV-infected cell population also expressed the CD15 and class II MHC DR antigens. By means of immunoselection procedures it was possible to show that a consistent proportion of HBLV-infectable cells were contained within the CD3-depleted immature T cell population, while the depletion of CD2+ cells completely abrogated the infectability of the cultures. Northern blot analysis confirmed the T cell origin of HBLV-infected cells, demonstrating the expression of full size TCR-alpha and -beta chain mRNA. In addition to fresh T cells, HBLV was able to infect normal T lymphocytes expanded in vitro with IL-2 for greater than 30 d. These results indicate that HBLV is selectively T cell tropic in the course of the in vitro infection of normal mononuclear cells and may therefore be directly involved in the pathogenesis of T cell related hematological disorders. In particular, in light of the cytopathic effect exerted in vitro on CD4+ T lymphocytes, a possible role of HBLV in immune deficiency conditions should be considered.

Association of human immunodeficiency virus type 1 (HIV-1) RNA level, CD4 cell percent, and mortality was examined in stored sera from 254 infected children in an intravenous immunoglobulin infection prophylaxis trial. Ninety-two children (36.2%) died (41 during the study, 51 during long-term follow-up). The geometric mean baseline HIV-1 RNA level was 104,626 copies/mL, and the mean CD4 cell percent was 25%. Relative risk of death (RR) was 2.1 if the baseline RNA level was > 100,000 copies/mL (95% confidence interval [CI], 1.4–3.0) and was 3.0 if the baseline CD4 cell percent was <15% (95% CI, 2.2–4.0). If RNA levels increased after baseline, the RR was 1.8 (95% CI, 1.3–2.6), and if the CD4 cell percent dropped to <15%, the RR was 2.8 (95% CI, 1.6–4.9). In a multivariate model, both baseline RNA level and CD4 cell percent were independently associated with mortality risk. In a time-dependent model, the RR per log10 increase in HIV-1 RNA copy numbers was 2.8 (95% CI, 2.1–3.6) and per 5 percentage point decrement in CD4 cell percent was 1.3 (95% CI, 1.2–1.5). Both variables should be considered for in decision-making regarding therapy and evaluation of antiretroviral response.

THE TREATMENT of human immunodeficiency virus (HIV) infection with antiretroviral compounds has recently undergone rapid progress. In parallel, the quantitation of plasma viral RNA and CD4⁺ lymphocytes has become the foundation on which prediction of clinical course and response to therapy is based. Most of this rapid change has resulted from clinical studies conducted in adult populations. Aggressive, multidrug regimens are currently being introduced into pediatric populations both in clinical practice as well as in controlled trials.^1-4 While plasma RNA and CD4⁺ lymphocyte quantitation data are being generated in children, it is unclear whether the experience and guidelines developed for adults^5-7 will be applicable to infants and children. Special issues that underscore this concern include the presence of a developing immune system at the time of infection followed by high levels of proliferating target cells and immune activation^8,9 and persistently high levels of plasma virus for extended periods in young children.^10-12