DIFFERENTIAL GENE-EXPRESSION IN RESPONSE TO ADJUNCTIVE RECOMBINANT HUMAN INTERLEUKIN-2 IMMUNOTHERAPY IN MULTIDRUG-RESISTANT TUBERCULOSIS PATIENTS

Administration of low-dose recombinant human interleukin 2 (rhuIL-2) i n combination with multidrug chemotherapy to patients with multidrug-r esistant tuberculosis (MDR TB) induces measurable changes in in vitro immune response parameters which are associated with changes in the cl inical and bacteriologic status of the patients. To determine the mole cular basis of these changes, we have used semiquantitative reverse tr anscriptase-initiated PCR (RT-PCR) and differential display technology . During rhuIL-2 treatment of MDR TB patients, decreased levels of gam ma interferon (IFN-gamma) mRNA in peripheral blood mononuclear cells ( PBMC) relative to baseline levels were observed. However, at the site of a delayed-type hypersensitivity (DTH) response to purified protein derivative of tuberculin (PPD), the expression of cellular IFN-gamma a nd IL-2 mRNAs was increased during rhuIL-2 therapy. Levels of other cy tokine mRNAs were not significantly affected by rhuIL-2 administration . Using differential-display RT-PCR, we identified several genes expre ssed at the DTH skin test site which were up-or down-regulated during rhuIL-2 treatment. Cytochrome oxidase type I mRNA was increased in res ponse to rhuIL-2, therapy relative to baseline levels, as was heteroge neous nuclear ribonuclear protein G mRNA. CD63, clathrin heavy chain, and beta-adaptin mRNAs, all of which encode proteins associated with t he endocytic vacuolar pathway of cells, were also differentially regul ated by rhuIL-2 administration. The differential effects of IL-2 were confirmed in vitro by using PBMC obtained from PPD-positive individual s stimulated with Mycobacterium tuberculosis and IL-2. The differentia l expression of genes may provide a surrogate marker for leukocyte act ivation at a mycobacterial antigen-specific response site and for the development of an enhanced antimicrobial response which may result in improved outcomes in MDR TB patients.