Author: V. Dimov, M.D., Allergist/Immunologist and Assistant Professor at University of Chicago
Reviewer: S. Randhawa, M.D., Allergist/Immunologist, Fort Lauderdale, FL
A 38-year-old male is at the allergy clinic here for evaluation of low CD4 count. The reason for checking his CD4 was that he volunteered to be involved in a research project 5 years ago. His absolute CD4 was 456 at the time. At that time, he was negative for both HIV-1 and HIV-2 type viruses, and the test was repeated in 3 years later. Since then, his CD4 count continues to be low. It was 432 three years ago. Despite the low CD4 count, however, he has no history of any infections or abnormalities related to it. He has history of difficulty gaining immunity against hepatitis B after vaccination, and after 3 separate vaccinations, he was not able to develop detectable IgG antibody against it. His flow cytometry from 3 years ago showed absolute CD4 count of 432, CD8 count of 379, CD19 count of 261, and CD56 count of 278. He had positive immunoglobulin G against measles and rubella 10 years ago. He does not recall any family history of immunodeficiency. He has no family history of allergic rhinitis, asthma or eczema or food allergy.
Past Medical History: As above. Past Surgical History: Negative. Current Medications: He is not on any medications on a regular basis. Family History: Unremarkable. Physical Examination: unremarkable.
What is the most likely diagnosis?
Idiopathic CD4 lymphocytopenia of unclear etiology at this point.
Any clues about the etiology of his idiopathic CD4 lymphocytopenia?
A variety of past or latent viral diseases can induce CD4 lymphocytopenia. Autoimmune conditions can also pay a role. In patients with asymptomatic CD4 lymphocytopenia in the absence of HIV infection and opportunistic infections, a genetic defect could be the cause.
What laboratory workup would you suggest?
Evaluate the function of the other parts of his immune system including B cells and T cells and humoral immunity.
Regarding his idiopathic CD4 lymphocytopenia, the suggested workup would include flow cytometry with CD4, CD3, CD8, CD19, CD26, CD56, and CD16, also immunoglobulin G subclasses, immunoglobulin G, A, M, and E, CBC with differential, immunoglobulin G titers for 23 pneumococcal serotypes, tetanus, diphtheria, hepatitis, and mumps, and also mitogen stimulation test for lymphocyte proliferation for B and T cells.
ANA, CMP, ESR and UA can also be addded to his laboratory work.
An evaluation by an infectious disease specialist for his lymphocytopenia is also suggested in order to rule out any latent viral infection that may play a role in his etiology.