To confirm results from a previous study in which the combination of thymopentin plus zidovudine ( AZT ), an antiretroviral agent, slowed disease progression in HIV-infected asymptomatic patients. To evaluate the efficacy and safety of thymopentin in HIV-infected asymptomatic patients receiving either monotherapy with AZT, didanosine ( ddI ), or stavudine ( d4T ), or combination antiretroviral therapy with AZT / ddI or AZT / zalcitabine ( ddC ).

Inclusion Criteria

Patients must have:

• Asymptomatic HIV infection.
• CD4 count 100-400 cells/mm3.
• No HIV-associated neurologic abnormalities or constitutional symptoms.
• No oral hairy leukoplakia.
• At least 6 months of prior AZT.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms or conditions are excluded:

• Abnormal chest x-ray, consistent with active opportunistic infection.
• Hypersensitivity to thymopentin.
• Significant chronic underlying medical illness.
• Grade 2 or worse peripheral neuropathy.

Concurrent Medication:

Excluded:

• HIV vaccines.
• Investigational or non-FDA approved medication.
• Immunomodulatory therapies.
• Experimental therapies.
• Any antiretroviral therapy other than AZT, ddI, ddC, d4T, or 3TC.

Patients with the following prior conditions are excluded:

• Herpes zoster (within the past year).
• Recurrent (> one episode) oral candidiasis (confirmed).
• Vulvovaginal candidiasis (persistent, frequent, or poorly responsive to therapy).
• Bacillary angiomatosis.
• Listeriosis.
• Idiopathic thrombocytopenia purpura.

Prior Medication:

Excluded at any time prior to study entry:

More than one dose of thymopentin.

Excluded within 30 days prior to study entry:

• HIV vaccines.
• Investigational or non-FDA approved medication.
• Immunomodulatory therapies.
• Experimental therapies.
• Any antiretroviral therapy other than AZT, ddI, ddC, d4T, or 3TC.

Required:

• Prior AZT (>= 300 mg/day) for at least 6 months; on current regimen (any combination of approved nucleoside analogues) for at least 4 weeks.

Significant active alcohol or drug abuse.