Studies on newly synthesized peptide as an immunoregulator against protozoan infection

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Newly synthesized peptide (Obioactin to Obiopeptides) of the activity units which were isolated from cytokines (lymphokines) as an immunoregulator were examined in the effect of Toxoplasma chronically infected animals. Mice chronically infected with Toxoplasma gondii were treated with cyclophosphamide (Cyp), Obiopeptide-1 (Obio-1) and/or anti-CD4 monoclonal antibody to determine the effect of these immunosuppressive agents on the cysts in the brain. In the brain of non-treated, and infected Cyp-Obi-1 treated mice, with hematoxyline-eosine staining or anti-Toxoplasma ABC lebelling staining, large typicallly rounded tissue cysts were mostly detected, and in some regioins dividing microcysts were also observed in this experimental sutdies. In contrast, brain tissue from Cyp only or anti-CD4 treated infected mice had multiple degenerated cysts of varied sizes in some brain regions, as well as clusters of microcysts, however, such change was more striking in the anti-CD4 treated mice. Infec … More ted mice treated with a combination of Cyp and Obi-1 showed a significantly higher survival of 80% compared to 20% survival in mice treated with Cyp only. Percent neutrophilic leucocytes, monocytes and lymphocytes in mice treated with a combination of Obio-1 and anti-CD4, or Obio-1 and Cyp were higher compared to those groups treated with anti-CD4 antibody, or Cyp only. The increase in neutrophilic leucocyte and lymphocyte counts after a combined Cyp and Obio-1 treatment may, like wise, contribute to the induction of resistance in mice against Toxoplasma gondii infection. These results indicate that reactivation of rupture of tissue cysts in mice treated with Cyp, chronically infected with Toxoplasma, mignt be mainly mediated by CD4 positive cells rather than other CD8 and CD5 cells.An immunoregulator or immunomodulator, such as Toxoplasma lysate antigen (TLA) was tested in our studies. In this studies, TLA induces in numbers of natural killer (NK) cells, cytotoxic T-lymphocytes (CTL) and lymphokine-activaed killer (LAK) cells in animals after TLA injection. The induction of these killer cells in animal bodies needs to exist in combination with macrophages and lymphocytes in their in vivo. An acitivity unit in TLA was isolated as TLA-Ig8, and the induction of the various killer cells in vivo and in vitro tests was significantly strong in comparison with others. Using the TLA-Ig8 monoclonal antibody, the structure of Ig8 is now making clear. Less