Publisher Summary HIV-1-related idiopathic thrombocytopenia (HIV-1-ITP) is an immunologic thrombocytopenic disorder first noted in patients with early HIV-1 infection. Patients with this disorder have increased circulating immune complexes and a reversal of the CD4/CD8 ratio. This chapter describes various studies on anti-idiotype antibodies in HIV-1-ITP patients. In a study serum circulating immune complexes of HIV-1-ITP, patients were precipitated with polyethylene glycol (PEG-IC). Presence of Ab with internal image Ab2β reactivity for anti-HIV-1gp120 was demonstrated in the cohort of HIV-1-infected patients studied. The chapter describes a procedure to produce a human mAb with anti-CD4 as well as anti-Id to anti-HIV-1gp120. Such a mAb could be a useful therapeutic agent for treating HIV-1 because the Ab should theoretically inhibit binding of HIV-1 to the CD4 receptor on T cells and act as an immunogen to produce Ab3 that would be an antibody against HIV-lgp120.