Low CD4+ counts in a study of transfusion safety. The Transfusion Safety Study Group

The Hitchhiker Guide to CD4+ T-Cell Depletion in Lentiviral Infection. A Critical Review of the Dynamics of the CD4+ T Cells in SIV and HIV Infection

CD4⁺ T-cell depletion is pathognomonic for AIDS in both HIV and simian immunodeficiency virus (SIV) infections. It occurs early, is massive at mucosal sites, and is not entirely reverted by antiretroviral therapy (ART), particularly if initiated when T-cell functions are compromised. HIV/SIV infect and kill activated CCR5-expressing memory and effector CD4⁺ T-cells from the intestinal lamina propria. Acute CD4⁺ T-cell depletion is substantial in progressive, nonprogressive and controlled infections. Clinical outcome is predicted by the mucosal CD4⁺ T-cell recovery during chronic infection, with no recovery occurring in rapid progressors, and partial, transient recovery, the degree of which depends on the virus control, in normal and long-term progressors. The nonprogressive infection of African nonhuman primate SIV hosts is characterized by partial mucosal CD4⁺ T-cell restoration, despite high viral replication. Complete, albeit very slow, recovery of mucosal CD4+ T-cells occurs in controllers. Early ART does not prevent acute mucosal CD4⁺ T-cell depletion, yet it greatly improves their restoration, sometimes to preinfection levels. Comparative studies of the different models of SIV infection support a critical role of immune activation/inflammation (IA/INFL), in addition to viral replication, in CD4⁺ T-cell depletion, with immune restoration occurring only when these parameters are kept at bay. CD4⁺ T-cell depletion is persistent, and the recovery is very slow, even when both the virus and IA/INFL are completely controlled. Nevertheless, partial mucosal CD4⁺ T-cell recovery is sufficient for a healthy life in natural hosts. Cell death and loss of CD4⁺ T-cell subsets critical for gut health contribute to mucosal inflammation and enteropathy, which weaken the mucosal barrier, leading to microbial translocation, a major driver of IA/INFL. In turn, IA/INFL trigger CD4⁺ T-cells to become either viral targets or apoptotic, fueling their loss. CD4⁺ T-cell depletion also drives opportunistic infections, cancers, and comorbidities. It is thus critical to preserve CD4⁺ T cells (through early ART) during HIV/SIV infection. Even in early-treated subjects, residual IA/INFL can persist, preventing/delaying CD4⁺ T-cell restoration. New therapeutic strategies limiting mucosal pathology, microbial translocation and IA/INFL, to improve CD4⁺ T-cell recovery and the overall HIV prognosis are needed, and SIV models are extensively used to this goal.

Idiopathic CD4 lymphocytopenia: clinical and immunologic characteristics and follow-up of 40 patients

Idiopathic CD4 T lymphocytopenia (ICL) is a rare and severe condition with limited available data. We conducted a French multicenter study to analyze the clinical and immunologic characteristics of a cohort of patients with ICL according to the Centers for Disease Control criteria.We recruited 40 patients (24 female) of mean age 44.2 ± 12.2 (19-70) years. Patients underwent T-lymphocyte phenotyping and lymphoproliferation assay at diagnosis, and experiments related to thymic function and interferon (IFN)-γ release by natural killer (NK) cell were performed. Mean follow-up was 6.9 ± 6.7 (0.14-24.3) years. Infectious, autoimmune, and neoplastic events were recorded, as were outcomes of interleukin 2 therapy.In all, 25 patients had opportunistic infections (12 with human papillomavirus infection), 14 had autoimmune symptoms, 5 had malignancies, and 8 had mild or no symptoms. At the time of diagnosis, the mean cell counts were as follows: mean CD4 cell count: 127/mm (range, 4-294); mean CD8: 236/mm (range, 1-1293); mean CD19: 113/mm (range, 3-547); and mean NK cell count: 122/mm (range, 5-416). Most patients had deficiency in CD8, CD19, and/or NK cells. Cytotoxic function of NK cells was normal, and patients with infections had a significantly lower NK cell count than those without (p = 0.01). Patients with autoimmune manifestations had increased CD8 T-cell count. Proliferation of thymic precursors, as assessed by T-cell rearrangement excision circles, was increased. Six patients died (15%). CD4 T-cell count <150/mm and NK cell count <100/mm were predictors of death.In conclusion, ICL is a heterogeneous disorder often associated with deficiencies in CD8, CD19, and/or NK cells. Long-term prognosis may be related to initial CD4 and NK cell deficiency.

Cryptococcal rib osteomyelitis as primary and only symptom of idiopathic CD4 penia

A 59-year old man with idiopathic CD4 lymphopenia presented with extensive disseminated Cryptococcus neoformans infection including a large rib cryptoccocoma, vertebral spondylitis and pleural empyema. Complete resection of the affected part of the rib was necessary after failure of initial antifungal treatment. The vertebral spondylitis has been successfully managed at 3 years of follow-up by continuous itraconazole treatment and regular MRI combined with leucocyte scintigraphy assessment.

Idiopathic CD4+ T lymphopenia without autoimmunity or granulomatous disease in the slipstream of RAG mutations

A girl presented during childhood with a single course of extensive chickenpox and moderate albeit recurrent pneumonia in the presence of idiopathic CD4+ T lymphocytopenia (ICL). Her clinical condition remained stable over the past 10 years without infections, any granulomatous disease, or autoimmunity. Immunophenotyping demonstrated strongly reduced naive T and B cells with intact proliferative capacity. Antibody reactivity on in vivo immunizations was normal. T-cell receptor-Vβ repertoire was polyclonal with a very low content of T-cell receptor excision circles (TRECs). Kappa-deleting recombination excision circles (KRECs) were also abnormal in the B cells. Both reflect extensive in vivo proliferation. Patient-derived CD34+ hematopoietic stem cells could not repopulate RAG2(-/-)IL2Rγc(-/-) mice, indicating the lymphoid origin of the defect. We identified 2 novel missense mutations in RAG1 (p.Arg474Cys and p.Leu506Phe) resulting in reduced RAG activity. This report gives the first genetic clue for ICL and extends the clinical spectrum of RAG mutations from severe immune defects to an almost normal condition.

Safety and efficacy of treatment using interleukin-2 in a patient with idiopathic CD4(+) lymphopenia and Mycobacterium avium-intracellulare

We present the case of a 39-year-old white man with a Myobacterium avium-intracellulare pulmonary infection found to have a CD4(+) count of 172 cells/mm(3) and diagnosed subsequently with idiopathic CD4(+) lymphopenia (ICL). After receiving clathromycin for 4 months with minimal improvement, the patient was started on pegylated subcutaneous interleukin (IL)-2 at 600,000 units daily. Later, he received incrementally higher pegylated IL-2 doses until he reached a maintenance dose 3 months later of 11 million units weekly divided into three equal doses. After 5 months of therapy, the patient's chronic cough resolved completely, sputum cultures became negative for Myobacterium avium-intracellulare and the CD4(+) T cell count increased to 553 cells/mm(3). After 35 months of well-tolerated IL-2 treatments and no recurrence of any opportunistic infections, IL-2 treatment was stopped. CD4(+) counts 6 and 9 months after discontinuing IL-2 treatment were 596 and 378 cells/mm(3) respectively, and he remains asymptomatic. This report supports IL-2 treatment for ICL-associated opportunistic infections as a safe and potentially efficacious treatment option, especially when combined with more traditional treatment regimens.

Idiopathic CD4+ lymphocytopenia: natural history and prognostic factors

Idiopathic CD4(+) lymphocytopenia (ICL) is a rare non-HIV-related syndrome with unclear natural history and prognosis. This prospective natural history cohort study describes the clinical course, CD4 T lymphocyte kinetics, outcome, and prognostic factors of ICL. Thirty-nine patients (17 men, 22 women) 25 to 85 years old with ICL were evaluated between 1992 and 2006, and 36 were followed for a median of 49.5 months. Cryptococcal and nontuberculous mycobacterial infections were the major presenting opportunistic infections. Seven patients presented with no infection. In 32, CD4 T-cell counts remained less than 300/mm(3) throughout the study period and in 7 normalized after an average of 31 months. Overall, 15 (41.6%) developed an opportunistic infection in follow-up, 5 (13.8%) of which were "AIDS-defining clinical conditions," and 4 (11.1%) developed autoimmune diseases. Seven patients died, 4 from ICL-related opportunistic infections, within 42 months after diagnosis. Immunologic analyses revealed increased activation and turnover in CD4 but not CD8 T lymphocytes. CD8 T lymphocytopenia (< 180/mm(3)) and the degree of CD4 T cell activation (measured by HLA-DR expression) at presentation were associated with adverse outcome (opportunistic infection-related death; P = .003 and .02, respectively).

Primary leptomeningeal lymphoma in a patient with concomitant CD4+ lymphocytopenia

BACKGROUND

Idiopathic CD4+ lymphocytopenia (ICL) is a rare disorder in which patients have mild and/or severe opportunistic infections or maybe without symptoms. The etiology is currently unknown. Diagnosis is made by excluding retroviral infections (human immunodeficiency virus-1 or -2, human T cell lymphotropic virus-1 or -2) or other known causes of immunosuppression.

OBJECTIVE

To provide a case report of a patient with possible ICL who presented with a rare form of primary non-Hodgkin lymphoma (NHL) of the central nervous system (CNS). Review of the literature has identified only five other patients with NHL and ICL; however, none of these had a CNS lymphoma.

RESULTS

We describe a patient with possible ICL, and address links between lymphopenia and lymphoproliferative disorders.

CONCLUSIONS

Although not uncommon for patients infected with human immunodeficiency virus to develop CNS NHL, this is the first case of a possible ICL patient with such a lymphoma. This case revisits an important relationship between lymphopenia and lymphoproliferative disorders.

Defective p56Lck activity in T cells from an adult patient with idiopathic CD4+ lymphocytopenia

Idiopathic CD4(+) lymphocytopenia (ICL) is defined by a stable loss of CD4(+) T cells in the absence of any known cause of immune deficiency. This syndrome is still of undetermined origin. It affects adult patients, some of them displaying opportunistic infections similar to HIV-infected subjects. The hypothesis that the cellular immune defect may be due to biochemical failures of the CD3-TCR pathway is investigated here in a patient associating a severe selective CD4(+) lymphocytopenia with an increased CD8(+) T cell count discovered in the course of a cryptococcal meningitidis. A 40% reduction of T cell proliferation to CD3-TCR stimulation is observed only in the CD4(+) subpopulation. The early CD3-induced protein tyrosine phosphorylations are conserved in both CD4(+) and CD8(+) subsets, and the levels of the T cell protein tyrosine kinases p56(Lck), p59(Fyn) and ZAP-70 are normal. However, we find a 50% reduction of p56(Lck) kinase activity in the patient's T cells compared to a healthy control donor. p59(Fyn) activity does not appear to be altered. Nevertheless, we do not find any genetic abnormality of p56(Lck). These results thus suggest that a defect of an unknown protein regulating p56(Lck) activity takes place in this patient's T cells. Taken together, these findings reveal p56(Lck) alteration in ICL and confirm the critical role of this kinase in the maintenance of the peripheral CD4(+) T cell subpopulation.

Antibodies against retroviral proteins and nuclear antigens in a subset of idiopathic CD4+ T lymphocytopenia patients

Idiopathic CD4+ T lymphocytopenia (ICL) is an immunodeficiency syndrome characterized by severe depletion of CD4+ T lymphocytes, but in which human immunodeficiency virus cannot be detected. Peripheral blood mononuclear cells (BPMCs) from an ICL patient were cocultured with HUT78 T-lymphoblastoid cells, and an acute cytopathic effect and formation of multinucleated cells were observed. A human intracisternal A-type retroviral particle designated HIAP-II was detected in cells surviving the acute cytopathic effect. Eight of 13 ICL patients in a blinded screen of a serological panel provided by the National Centers for Disease Control and Prevention (CDC) had serum antibodies that specifically reacted with HIAP-II associated proteins by Western immunoblotting. None of 19 control sera in the panel that were unreactive with HIV Gag proteins produced a positive result on HIAP-II immunoblots. Comparable results were obtained in a blinded screen of a second CDC serological panel. Sera from 8 of 14 ICL patients in the second serological panel were positive for antinuclear autoantibodies (ANAs) commonly observed in patients with systemic autoimmune diseases. These results suggest the possible involvement of an A-type retrovirus or autoimmunity in development of ICL in a subset of patients.

Idiopathic CD4+ T-lymphocytopenia in HIV seronegative men with hemophilia and sex partners of HIV seropositive men. Multicenter Hemophilia Cohort Study

Persons with hemophilia or other HIV-1 risk factors may be more likely to have idiopathic CD4+ T-lymphocytopenia (ICL). We determined the frequency of ICL in prospectively followed cohorts of HIV-1 seronegative hemophilic men and seronegative female sex partners of HIV-1 infected hemophilic men, and examined factors potentially associated with ICL. Seven of 304 (2.3%) seronegative hemophilic men and one of 160 (0.6%) female partners met the ICL definition, but the condition resolved for two of the men and for the sole female partner. All five men with persistent ICL had lymphocytopenia (< 1,200 total lymphocytes/microliters) and < 300 total CD4+ lymphocytes/microliters; only one had a low CD4+ percentage. On the most recent measurement, 14.5% of the 304 seronegative hemophilic men had lymphocytopenia. Compared with matched hemophilic controls, men with persistent ICL more often had a history of liver disease (3/5 cases, 0/21 controls, P = 0.007) or splenomegaly (3/5 cases, 4/21 controls; P = 0.04), but not severe hemophilia, greater clotting factor concentrate exposure, high alanine aminotransferase levels, hepatitis B virus antigenemia, or detectable hepatitis C virus RNA in plasma. All five cases and 20/21 controls had antibodies to hepatitis C virus present in their serum. In this cohort of hemophilic men, ICL was related to lymphocytopenia associated with liver disease rather than selective loss of CD4+ lymphocytes.

Idiopathic CD4+ T-lymphocytopenia: analysis of a patient with selective IgA deficiency and no evidence of HIV infection

Idiopathic CD4+ T-lymphocytopenia (ICL) in HIV-seronegative patients is a newly described, rare entity. The common underlying abnormality is a usually stable depletion in CD4+ lymphocytes in patients, some of which have unexplained opportunistic infections. We present a previously unreported condition of an asymptomatic individual with CD4+ T-lymphocytopenia and a selective IgA deficiency. The subject is a 35-year-old healthy white male with a documented 5-year history of low CD4+ T cell counts. He has been repeatedly HIV seronegative and has no risk factors for HIV infection. Data were obtained from several laboratories over a 5-year period and include standard WBC differentials, HIV testing, serum immunoglobulin quantitation, mitogen stimulation assays, diphtheria and tetanus antitoxin titers, and flow cytometric immunophenotyping. The composite results show a subject with a normal white blood cell count, an absolute lymphopenia, a slight granulocytosis, and a selective IgA deficiency. Leukocyte subset analyses show essentially normal B but significantly altered T cell phenotypes. The normal CD4:CD8 ratio shows extreme inversion, primarily due to CD4 T-lymphocytopenia.

Idiopathic CD4+ T-lymphocytopenia--an analysis of five patients with unexplained opportunistic infections

BACKGROUND

Although patients with idiopathic CD4+ T-lymphocytopenia and serious opportunistic infections have been described previously, the clinical and immunologic features of this condition have not been well defined.

METHODS

We studied in detail five patients with idiopathic CD4+ T-lymphocytopenia. The studies included serologic testing, culture, and polymerase chain reaction for the human immunodeficiency virus (HIV) types 1 and 2, serologic testing for the human T-cell lymphotropic virus (HTLV) types I and II, lymphocyte phenotyping, immunoglobulin quantitation, and lymphocyte-transformation assays, as well as attempts to isolate a retroviral agent. The results were compared with those in HIV-infected persons matched for CD4+ T-cell counts and with those in normal controls. We also studied the spouses of patients and the blood donors for one patient.

RESULTS

In these five patients, there was no evidence of either HIV or HTLV infection. All the patients had both low percentages and low counts of CD4+ T cells, with relative increases in percentages, but not counts, of CD8+ cells. Numbers of B cells and natural killer cells were generally normal. As compared with HIV-infected persons, our patients had lower percentages and counts of CD8+ cells and more lymphopenia. CD4+ counts were relatively stable over time. Instead of the high immunoglobulin levels seen in HIV infection, these patients had normal or slightly low levels of immunoglobulins. The lymphocyte-transformation response to mitogens and antigens was depressed. Results in spouses and blood donors were normal.

CONCLUSIONS

Idiopathic CD4+ T-lymphocytopenia differs from HIV infection in its immunologic characteristics and in its apparent lack of progression over time. Nothing about the immunologic or viral-culture studies performed in these patients or about their family members or blood donors suggests that a transmissible agent causes this condition.

Unexplained opportunistic infections and CD4+ T-lymphocytopenia without HIV infection. An investigation of cases in the United States. The Centers for Disease Control Idiopathic CD4+ T-lymphocytopenia Task Force

BACKGROUND

The clinical and public health importance of recent reports of patients with CD4+ T-lymphocytopenia without human immunodeficiency virus (HIV) infection is unclear. We conducted investigations to determine the demographic, clinical, and immunologic features of patients with idiopathic CD4+ T-lymphocytopenia; whether the syndrome is epidemic or transmissible; and the possible causes.

METHODS

We reviewed 230,179 cases in the Centers for Disease Control and Prevention (CDC) AIDS Reporting System and performed interviews, medical-record reviews, and laboratory analyses of blood specimens from adults and adolescents who met the CDC case definition of idiopathic CD4+ T-lymphocytopenia (< 300 CD4+ cells per cubic millimeter or a CD4+ cell count < 20 percent of total T cells on two occasions and no evidence of infection on HIV testing), their sexual contacts, household contacts, and persons who had donated blood to them.

RESULTS

We interviewed 31 of the 47 patients identified with idiopathic CD4+ T-lymphocytopenia and 23 of their contacts. There were 29 male and 18 female patients, with a mean age of 43 years (range, 17 to 78); 39 were white, 4 were Asian, 2 were Hispanic, and 2 were black. Eighteen patients (38 percent) had one or more risk factors for HIV infection: seven had hemophilia, six had engaged in homosexual sex, six had received blood transfusions, and two had had heterosexual sex partners who were at risk for HIV infection. The other 29 patients (62 percent) had no identified risk factors for HIV infection. Nineteen persons (40 percent) had AIDS-defining illnesses (18 had opportunistic infections), 25 (53 percent) had conditions that were not AIDS-defining, and 3 (6 percent) were asymptomatic. We tested blood from 28 patients: 8 (29 percent) were found to have CD4+ T-lymphocyte counts of less than 300 cells per cubic millimeter, and 6 had CD8+ T-lymphocytopenia (< 250 cells per cubic millimeter). Ten sex partners, three household contacts, and four children of the patients, as well as six persons who had donated blood to the patients, were immunologically and clinically normal.

CONCLUSIONS

This investigation of patients with idiopathic CD4+ T-lymphocytopenia and unexplained opportunistic infections indicates that the disorder is rare and represents various clinical and immunologic states. The investigation of contacts revealed no evidence of a new transmissible agent that causes lymphocytopenia.