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Interaction of staphylococcal fibronectin binding protein (FnBP), TSST-1 and alpha-toxin with murine lymphocytes
1Department of Medical Microbiology, University of Lund, Sweden.
The most restrictive factor in the inductive phase of immune response is the contact and adhesion of antigen-presenting cells and responding lymphocytes. We report the in vitro formation of aggregates (clusters) of murine T lymphocytes and dendritic cells (DC) pulsed with highly purified staphylococcal toxins (TSST-1, alpha-toxin) and gene-cloned surface fibronectin binding protein (gal-FnBP). A high percentage of T lymphocytes were involved in clustering with TSST-1-pulsed DC. Lymphocytes of mice infected with Staphylococcus aureus (strain Cowan 1) 21 days before testing, clustered with the same ability as cells of mice infected 3 days before. Dendritic cells pulsed with alpha-toxin formed a moderate number of clusters only when co-cultured with T lymphocytes of mice infected 3 days before the test. FnBP-pulsed DC aggregated strongly with T lymphocytes. This response peaked at 3-4.5 h-cultures and increased again after 24 h. We concluded that at the beginning of co-culture, FnBP amplified the cells' adhesion process on antigen-independent way. This conclusion is supported by the observation that DC pulsed with formalin-modified FnBP (with a 65% decreased ability to bind fibronectin) formed fewer clusters with T-immune cells than dendritic cells pulsed with native, non-treated FnBP.
The most restrictive factor in the inductive phase of immune response is the contact and adhesion of antigen-presenting cells and responding lymphocytes. We report the in vitro formation of aggregates (clusters) of murine T lymphocytes and dendritic cells (DC) pulsed with highly purified staphylococcal toxins (TSST-1, alpha-toxin) and gene-cloned surface fibronectin binding protein (gal-FnBP). A high percentage of T lymphocytes were involved in clustering with TSST-1-pulsed DC. Lymphocytes of mice infected with Staphylococcus aureus (strain Cowan 1) 21 days before testing, clustered with the same ability as cells of mice infected 3 days before. Dendritic cells pulsed with alpha-toxin formed a moderate number of clusters only when co-cultured with T lymphocytes of mice infected 3 days before the test. FnBP-pulsed DC aggregated strongly with T lymphocytes. This response peaked at 3-4.5 h-cultures and increased again after 24 h. We concluded that at the beginning of co-culture, FnBP amplified the cells' adhesion process on antigen-independent way. This conclusion is supported by the observation that DC pulsed with formalin-modified FnBP (with a 65% decreased ability to bind fibronectin) formed fewer clusters with T-immune cells than dendritic cells pulsed with native, non-treated FnBP.