Understanding the rate of lymphocyte replication and destruction in HIV-infected patients, as well as the effects of therapy on lymphocyte replication should lead to a better understanding of the mechanisms behind the immunodeficiency induced by HIV. To examine this directly, up to 100 HIV-infected patients will receive up to 5 days of continuous infusions with [6,6-(2)H(2)]-glucose, a nonradioactive, stable isotope of glucose that is safe to administer. The deuterium is incorporated into DNA via metabolism of glucose to ribose and incorporation into nucleotides. The rate of incorporation can be measured in subpopulations of cells to determine the rate of replication of those cells. Fifty HIV-uninfected persons will also be enrolled in the protocol to allow a determination of lymphocyte kinetics in individuals with normally functioning immune systems or immune systems that may have been affected by other diseases. All participants in this study will be reimbursed for the inconvenience and discomfort associated with study participation.