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LPF-induced T cell colony formation: effect of PMA and interleukin-2, and surface marker analysis
Abstract:
We demonstrated that a primary exposure to the lymphocytosis promoting factor (LPF) of Bordetella pertussis-induced T cell colony formation. Colony formation was observed when mononuclear cells (MNC) were cultured at concentrations of more than 1 X 10(6)/ml, and reached a peak on day 8. However, the number of colonies generated with LPF was about one-third induced with phytohaemagglutinin (PHA). Removal of monocytes from MNC or T cells resulted in the failure of colony formation, but colony growth could be restored by the addition of monocytes or B enriched cells, indicating that they were required for the optimal colony growth induced by LPF. In the absence of accessory cells, optimal colony growth from monocyte depleted T cells could be obtained when an appropriate concentration of phorbol myristate acetate (PMA) or interleukin-2 (IL-2) was added in the cultures with LPF. PMA did not enhance LPF-induced colony formation in the cultures containing a sufficient amount of exogeneous IL-2. These findings suggest that IL-2 is essential to LPF-induced colony formation. Surface marker analysis showed that most of LPF-induced colony cells were T cells. The percentages of T4+ and T gamma cells of LPF-induced colony cells were more, and T8+ cells less, than those of PHA-induced colony cells. Ia1, T9 and Tac antigens were detected on many colony cells induced by LPF or PHA. These results indicate that the phenotype of LPF-induced colony cells differs from those of PHA, but the sequential antigen expression on lymphocytes triggered by IL-2 might be similar in both LPF- and PHA-induced colony formation.
Insights
Bordetella pertussis lymphocytosis promoting factor (LPF) induces T cell colony formation, requiring accessory cells like monocytes. Interleukin-2 (IL-2) is essential for this LPF-induced T cell growth.
Area of Science:
- Immunology
- Cell Biology
Background:
- The lymphocytosis promoting factor (LPF) from Bordetella pertussis is known to affect lymphocytes.
- T cell colony formation is a key indicator of T cell activation and proliferation.
Purpose of the Study:
- To investigate the role of LPF in inducing T cell colony formation.
- To elucidate the cellular and molecular requirements for LPF-induced T cell growth.
Main Methods:
- Mononuclear cells (MNCs) were cultured with LPF, and colony formation was assessed.
- Accessory cell depletion and addition experiments were performed.
- Phorbol myristate acetate (PMA) and interleukin-2 (IL-2) were used to study colony growth.
- Surface marker analysis (T4, T gamma, T8, Ia1, T9, Tac) was conducted on colony cells.
Main Results:
- LPF induced T cell colony formation in MNCs at concentrations >1x10^6/ml, peaking on day 8.
- Monocytes and B cells were required for optimal LPF-induced colony growth, but IL-2 or PMA could substitute for accessory cells.
- IL-2 was found to be essential for LPF-induced colony formation.
- LPF-induced colony cells were predominantly T cells, with a distinct phenotype (more T4+ and T gamma+, fewer T8+) compared to phytohemagglutinin (PHA)-induced colonies.
Conclusions:
- LPF is a potent inducer of T cell colony formation.
- Accessory cells and IL-2 play critical roles in LPF-mediated T cell proliferation.
- The phenotype of LPF-induced T cell colonies differs from PHA-induced colonies, suggesting distinct activation pathways.