Idiopathic CD4 positive T-lymphocytopenia

Other Names: IMMUNODEFICIENCY 13; IMD13; ICL; IDIOPATHIC CD4 LYMPHOPENIA; Idiopathic CD4 lymphocytopenia

Idiopathic CD4 positive T-lymphocytopenia (ICL) is a rare disorder of the immune system. People with ICL have low levels of a type of white blood cell, called a CD4+ T cell. These low levels can not be explained by other causes of immunodeficiency, including HIV infection. T cells have many jobs in our immune system, such as attacking bacteria and viruses. CD4 is a protein found on the surface of many different cells within your immune system. It lets the different cells of your immune system work with each other. When CD4+ T cells are decreased, your body becomes more prone to infection.

Cause

The cause of ICL is not well understood. Contributing factors may be related to CD4+ T cell development and function, various deficiencies of the immune system, and genetic factors.

Signs and symptoms

The signs and symptoms of ICL usually become apparent in adulthood; although the age at time of diagnosis ranges from 1 year of age to 58 years of age. While some individuals may be asymptomatic, most come to medical attention after diagnosis of an infection related to a weakened immune system, called an opportunistic infection. These infections are similar to illnesses found in individuals with AIDS and may include: Bacterial: Mycobacterium, Salmonella, Nocardia Fungal: Candidiasis, Cryptococcus, Histoplasmosis Viral: Cytomegalovirus, varicella zoster virus, human papillomaviruses Parasitic: Toxoplasmosis, leishmaniasis Autoimmune disorders including Sjögren syndrome, sarcoidosis, psoriasis, autoimmune hemolytic anemia, and lupus and malignancies (cancers) including squamous cell carcinoma, and lymphoma may also occur.

Diagnosis

There are no universal diagnostic criteria for ICL; however, it should be suspected in an individual with laboratory findings including CD4+ T cell counts below 300 cells/mm3 or less than 20 percent of total lymphocytes in the absence of other immunodeficiencies, including HIV.

The following diseases may also cause decreased CD4+ T cell counts and could be considered as an alternative diagnosis: acute or chronic retroviral infections (HIV, human T-lymphotropic virus type 1), sarcoidosis, common variable immunodeficiency, congenital immunodeficiencies, and immunosuppressive states induced by chemotherapy, acute respiratory distress syndrome, or autoimmune disorders.

Treatment

Treatment of ICL mainly focuses on managing associated symptoms. For individuals without symptoms, regular measurement of CD4+ T cell counts and antibiotic use may be suggested. There are no guidelines regarding how frequently monitoring should occur. Two different methods to increase CD4+ T cell counts have been used on a few affected individuals with varying levels of success: Interleukin-2 (IL2) and bone marrow transplantation. IL2 is a type of protein naturally occurring in the immune system that works to increase the production and function of the immune system. A bone marrow transplant is a procedure to replace damaged or destroyed bone marrow (soft, fatty tissue inside your bones that produces blood cells) with healthy bone marrow stem cells. Stem cells are immature cells in the bone marrow that give rise to all of your different blood cells.

Prognosis

The long-term outlook (prognosis) for individuals with ICL varies depending on the extent of immunosuppression and the associated symptoms. Rarely, ICL can be a temporary finding that reverses over time. In most cases the level of CD4+ T cells stabilizes, rather than continuing to decrease.

NIH genetic and rare disease info

• NIH info on Idiopathic CD4 positive T-lymphocytopenia

Idiopathic CD4 positive T-lymphocytopenia is a rare disease.

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