An observational study in Idiopathic CD4+ Lymphocytopenia, Cryptococcal Meningitis and Warts, sponsored by National Institute of Allergy and Infectious Diseases (NIAID). Recruiting at 1 site in United States. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-09.
Sponsored by National Institute of Allergy and Infectious Diseases (NIAID) · Observational
Background:
Objectives:
Eligibility:
Design:
Idiopathic CD4+ lymphocytopenia (ICL) is a disorder characterized by decreased numbers of circulating CD4+ T lymphocytes in the absence of known causes of CD4+ lymphocytopenia. ICL is defined as an absolute CD4+ T cell count of less than 300 cells/microL in a patient with no human immunodeficiency virus infection or known immunodeficiency syndrome. The causes and frequency of the disorder remain unknown. The condition is typically diagnosed when patients present with a serious infection. In this natural history protocol, we will evaluate patients with CD4+ T cell counts below 300 cells/microL. We propose to follow 300 ICL patients for a minimum of 4 and maximum of 20 years, with a particular focus on the association between ICL and autoimmune disease. In addition to the ICL patients, we will enroll blood relatives and household contacts to better understand pathogenesis and etiologies of the syndrome. We will collect blood and other tissues for immunologic, rheumatologic, and genetic testing in an effort to identify and understand the underlying defects that cause ICL and follow its course in a cohort of patients who will receive best standard therapy for opportunistic infections.
54 studies on the registry are indexed under Meningitis, Cryptococcal; 6 are open to participants now.
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Adults with idiopathic CD4+ lymphocytopenia (ICL) who have CD4 \<300/microliters or \< 20% of total T cells and their blood relatives and household contacts.
To be eligible for this study, patients must satisfy all of the following inclusion criteria:
ICL PARTICPANT EXCLUSION CRITERIA:
Patients will be ineligible for this study if they satisfy any of the following criteria:
BLOOD RELATIVE INCLUSION CRITERIA:
To be eligible for study participation as a blood relative, subjects must be greater than or equal to 18 years of age and be a blood relative of an individual who meets or has met the CDC criteria for ICL.
HOUSEHOLD CONTACT INCLUSION CRITERIA:
To be eligible for study participation as a household contact, subjects must be greater than or equal to18 years of age and live within the same household as an ICL subjects participating in this protocol. Blood relatives who are household contacts are eligible to participate.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
CD4 count
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Blood Relatives of ICL subjects
Household contacts of ICL subjects
Patients with confirmed idiopathic CD4 lymphocytopenia
CD4 <300/microliters or < 20% of total T cells and their blood
To further characterize the natural history of ICL while also investigating the genetic, environmental, and immunologic features of the condition.
Time frame: Baseline and annually
Determine CD4+ T cell turnover, survival, functionality and cytokineresponsiveness in selected ICL patients.
Collection of research blood (PBL, serum and plasma) for storage
Time frame: Baseline and annually
Investigate ICL immune cell homeostasis and trafficking by immunologic studies including tissue biopsies and the utilization of ahumanized mouse model.
Collection of research blood (PBL, serum and plasma) for storage
Time frame: Baseline and annually
Establish the prognosis of CD4 lymphocytopenia, with particular focus on defining subgroups of patients according to the decline, stabilization, or rise of CD4+T cell counts over time.
Collection of research blood (PBL, serum and plasma) for storage
Time frame: Baseline and annually
Determine whether measurable immunologic parameters correlate with the development of opportunistic infections or other co-morbidities
Determine whether measurable immunologic parameters correlate with the development of opportunistic infections or other co-morbidities such as lymphoma in patients with ICL. Investigate the associations between idiopathic CD4+ lymphocytopenia and autoimmunity.Collection of research blood (PBL, serum and plasma) for storage
Time frame: Baseline and annually
Determine the relationship between ICL and the microbiome.
Collection of rectal swab and dietary questionnaire
Time frame: Baseline and annually
Started Jul 2009 (actual).
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