Thymomodulin enhances phagocytic and intracellular killing activities of polymorphonuclear leucocytes without increasing release of chemotactic factors.
Thymomodulin, a calf thymus derivative, is able to stimulate T-lymphocytes and monocytes, and to activate phagocytes and their precursors. However, it is not fully understood whether the effect of thymomodulin on phagocytic cells is a direct stimulation, or a phenomenon mediated by cytokines released by mononuclear cells. To answer this question, we first evaluated the effects of thymomodulin on the phagocytosis and intracellular killing of Staphylococcus aureus by blood polymorphonuclear cells (PMNs), cultured with or without autologous mononuclear cells. Secondly, during the processes of phagocytosis and intracellular killing, we evaluated the release by PMNs of chemotactic factors for PMNs, lymphocytes and monocytes. No difference was found in the phagocytosis and killing processes when PMNs were incubated alone or with autologous mononuclear cells (p > 0.05, each comparison). Thymomodulin was able to increase the phagocytosis process when PMNs were incubated with lymphocytes and monocytes (p = 0.05), and to enhance the killing by PMNs cultured alone (p = 0.05), or cultured with autologous mononuclear cells (p < 0.05). The release of chemotactic factors for PMNs, lymphocytes and monocytes in the supernatants of the phagocytosis experiments, was higher when PMNs were incubated with mononuclear cells, compared to cultures of PMNs alone (p < 0.05, each comparison); and thymomodulin did not increase their release without the presence of autologous mononuclear cells in the cultures (p > 0.05 each comparison). These data suggest that thymomodulin acts upon PMNs, inducing mononuclear cells to release factors able to stimulate the phagocytosis and the intracellular killing of exogenous organisms, but does not amplify the immune reaction enhancing further leucocytes recruitment.
Lantero
S
S
Division of Pneumology, G. Gaslini Institute, Genoa, Italy.
Oddera
S
S
Silvestri
M
M
Ottolini
V
V
Sacco
O
O
Rossi
G A
GA
D002469:Cell Separation; D002478:Cells, Cultured / Q000187:drug effects / Q000276:immunology; D002630:Chemotactic Factors / Q000378:metabolism*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000276:immunology; D006801:Humans; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000276:immunology; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology; D010587:Phagocytosis / Q000187:drug effects* / Q000276:immunology; D013211:Staphylococcus aureus; D013268:Stimulation, Chemical; D013949:Thymus Extracts / Q000494:pharmacology*
D002630:Chemotactic Factors; D013949:Thymus Extracts; C051006:thymomodulin