[Idiopathic CD4 lymphocytopenia]
Insights
Idiopathic CD4 lymphocytopenia is a rare syndrome defined by low CD4+ T-cell counts without HIV. This condition, distinct from HIV infection, is likely a primary immunodeficiency.
Area of Science:
- Immunology
- Virology
- Clinical Medicine
Background:
- CD4+ lymphocyte counts are stable in healthy adults but drop sharply in HIV infection, serving as a predictive marker.
- Case reports of non-HIV immunosuppression prompted a search for other retroviruses, but none were found.
- The Centers for Disease Control and World Health Organization defined Idiopathic CD4 Lymphocytopenia (ICL).
Discussion:
- ICL is characterized by CD4 counts below 300/mm3 or <20% of lymphocytes in successive counts, without HIV antibodies or known causes of immune deficiency.
- The syndrome is extremely rare, likely not new, with no known endemic zones or human-to-human transmission.
- Clinical presentation differs from HIV, with relative CD4 count stability and absence of hypergammaglobulinaemia despite susceptibility to opportunistic infections.
Key Insights:
- No evidence of an immunosuppressive retrovirus other than HIV has been found.
- Idiopathic CD4 Lymphocytopenia is a distinct clinical syndrome.
- ICL is proposed to be a primary immunodeficiency syndrome.
Outlook:
- Further research is needed to understand the pathogenesis of Idiopathic CD4 Lymphocytopenia.
- Investigating potential genetic or environmental factors contributing to ICL is warranted.
- Developing targeted therapies for ICL may improve patient outcomes.
Abstract:
In healthy adults the CD4+ lymphocyte count in circulating blood is remarkably stable over a prolonged period. In patients infected with the human immunodeficiency virus (HIV) CD4 counts drop off sharply and can be used as a predictive marker of midterm outcome. However certain case reports of patients with out HIV infection, some reported as early as 1983, have led to a much publicized search for another immunosuppressive retrovirus. In reality no evidence of any such virus has been found and the Centers for Disease Control and the World Health Organisation have now defined the syndrome of idiopathic CD4 lymphocytopenia which includes a CD4 count below 300/mm3 or less than 20% of total lymphocytes in at least two successive counts without anti-HIV antibodies and without a known cause of immune deficiency or immunosuppressor treatment. The syndrome is extremely rare and although only recently identified, is probably not new. No endemic zone is known and there is no evidence of inter-human transmission. The clinical presentation is different from HIV infection. Although patients are susceptible to opportunistic infections, CD4 counts have relative stability and no hypergammaglobulinaemia occurs. Idiopathic CD4 lymphopenia is probably a primary immunodeficiency syndrome.
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