• INCLUSION CRITERIA:

  18 years or older.

Documented HIV infection (ELISA/Western blot positive or, for acute seroconverters, PCR positive).

Able to provide informed consent and willing to comply with study requirements and clinic policies.

Negative urine or serum pregnancy test (for women of childbearing potential). In addition, women of childbearing potential must agree to practice abstinence or use two methods of birth control / contraception for 4 weeks prior to and 2 weeks after each BrDU infusion. Similarly, all men must agree to practice abstinence or use a condom when engaging in intercourse during the same time period.

Hemoglobin greater than 9 mg/dl; platelets greater than 50,000/mm(3); neutrophils greater than 750 cells/mm(3).

AST/ALT less than 300 IU/ml.

Less than Grade 2 level toxicity for other laboratory parameters.

EXCLUSION CRITERIA:

Active substance abuse or prior history of substance abuse which may interfere with protocol compliance.

Psychiatric illness or disturbance which, in the assessment of the protocol team, may affect safety or compliance.

Significant underlying cardiac, pulmonary, renal, gastrointestinal, rheumatologic or CNS disease as detectable on routine history, physical exam, or screening laboratory studies.

Pregnancy or breast-feeding.

Ongoing therapy with topical or systemic 5-fluorouracil.

Willingness to allow stored samples to be used for future studies of HIV infections and immunological function, and willingness to have HLA typing performed.

Patients who are virologic responders and immunologic non-responders (10-15 patients):

Plasma HIV less than 500 copies/ml by bDNA or RT-PCR for 1 year while receiving HAART, which includes at a minimum 3 antiretroviral drugs, at least one of which is a protease inhibitor or non-nucleoside reverse transcriptase inhibitor, and plasma HIV less than 50 copies /ml by the bDNA assay, performed at the NIH, within the 4 weeks prior to enrollment;

CD4 count less than 300 cells/mm(3) on 2 occasions at least one week apart, with no documented CD4 count greater than 350 cells/mm(3) during the prior 6 months;

No ongoing opportunistic infection or malignancy.

Patients who are virologic and immunologic responders (10-15 patients, matched if possible to study group for age (+/- 5 years) and duration of HAART therapy (+/- 6 months):

Plasma HIV less than 500 copies/ml by bDNA or RT-PCR for 1 year while receiving HAART, which includes at a minimum 3 antiretroviral drugs, at least one of which is a protease inhibitor or non-nucleoside reverse transcriptase inhibitor, and plasma HIV less than 50 copies/ml by the bDNA assay, performed at the NIH, within the 4 weeks prior to enrollment;

CD4 count greater than 350 cells/mm(3) on 2 occasions at least one week apart; CD4 count prior to the initiation of HAART therapy documented to be less than 300 cells/mm(3);

No ongoing opportunistic infection or malignancy.

For all patients: Willingness to have a CT scan of the thymus, to be performed under protocol 95-I-0027.