The combined administration of thymomodulin and interleukin 2 reverses T-cell unresponsiveness in mice infected with Mycobacterium bovis-BCG

Thymomodulin stimulates phagocytosis in vitro by rat macrophages and human polymorphonuclear cells

Activation of non-specific host defenses can increase resistance to infection in patients and especially those with reduced immune response. Thymomodulin is a calf thymic derivative containing low molecular weight peptides, which exerts immunomodulating activity probably through an enhancement of lymphocyte functions. To explore this possibility, rat macrophages (MP) and human polymorphonuclear (HPMN) cells were incubated in vitro with 100, 200, 400 micrograms/ml of thymomodulin at 37 degrees C for 60 min and their phagocytic activity was investigated. The number of phagocytosing cells was significantly increased following increasing concentrations of thymomodulin and the percentage of phagocytosis was increased more for human PMNs in comparison with rat MP, while the values of the phagocytic index were not modified after challenge with thymomodulin both for MPs and HPMNs.

The combined treatment of human peripheral blood mononuclear cells with thymolymphotropin and interleukin 2 increases PPD-driven T-cell proliferation and IL-2 induced cellular cytotoxicity against HIV-infected cells

Two in vitro systems (the DNA synthetic response to mycobacterial antigens and cytotoxicity against lymphoid cells) were used to analyse the effect of thymolymphotropin (TLT) on peripheral blood mononuclear cells (PBMC). Purified protein derivative of mycobacteria (PPD)-driven T-cell proliferation in low-responder donors was increased by the combined treatment with TLT and suboptimal doses of recombinant interleukin 2 (IL-2). Similarly, the activities of natural killer (NK) cells and lymphokine-activated killer (LAK) cells have been enhanced in PBMC cultures pretreated with TLT. Also, TLT showed an enhancing effect on the development of LAK cells capable of lysing Epstein-Barr virus (EBV)-transformed B-lymphocytes infected or uninfected with the human immunodeficiency virus (HIV).

Thymomodulin: biological properties and clinical applications

Thymomodulin (Ellem Industria Farmaceutica s.p.a., Milan, Italy) is a calf thymus acid lysate derivative, composed of several peptides with a molecular weight range of 1-10 kD. Thymomodulin did not exhibit any mutagenic effect. Furthermore, thymomodulin used in animal studies showed no toxicity even when used at high concentrations. Of major significance are the observations in murine and human systems that thymomodulin remains active when administered orally. In vitro and in vivo administered thymomodulin was able to induce the maturation of T-lymphocytes. Additionally, studies in vitro showed that this thymic derivative can enhance the functions of mature T-lymphocytes with cascading effects on B-cell and macrophage functions. Extensive human clinical trials with thymomodulin showed that this agent can improve the clinical symptoms observed with various disease processes, including infections, allergies and malignancies, and can improve immunological functions during ageing.