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Regulation of freshly isolated, IL-4-producing T cells: IFN-gamma-sensitive and -resistant cells
M F Naujokas1, E Schmitt, A Finnegan
1Department of Immunology/Microbiology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612.
Cytokine responsiveness of interleukin-4 (IL-4)-producing T cells (IL-4p) during primary in vitro stimulation was investigated. Freshly isolated T cells were stimulated with anti-CD3 epsilon antibodies in the presence of macrophages. Using limiting dilution analysis, we found that IL-4p were not detected when endogenous IL-2 activity was blocked with anti-IL-2 antibodies. These data support previous observations that IL-4p require IL-2 for induction, and further indicate the presence of macrophages was not sufficient to overcome the requirement for IL-2. The effects of IFN-gamma on IL-4p were studied in this system. Addition of exogenous IFN-gamma decreased the frequency of IL-4p but did not completely inhibit induction of these cells. Furthermore, blocking endogenous IFN-gamma during stimulation resulted in a 2- to 4-fold increase in the frequency of IL-4p detected. These data demonstrate the novel finding that both IFN-gamma-resistant and IFN-gamma-sensitive IL-4p were present in freshly isolated T cell populations. Thus, during early in vitro culture, there were at least two types of IL-4p, both of which require IL-2. These data indirectly support a current model of Th ontogeny as defined by cytokine production patterns, and extend the model to include cytokine responsiveness.
Cytokine responsiveness of interleukin-4 (IL-4)-producing T cells (IL-4p) during primary in vitro stimulation was investigated. Freshly isolated T cells were stimulated with anti-CD3 epsilon antibodies in the presence of macrophages. Using limiting dilution analysis, we found that IL-4p were not detected when endogenous IL-2 activity was blocked with anti-IL-2 antibodies. These data support previous observations that IL-4p require IL-2 for induction, and further indicate the presence of macrophages was not sufficient to overcome the requirement for IL-2. The effects of IFN-gamma on IL-4p were studied in this system. Addition of exogenous IFN-gamma decreased the frequency of IL-4p but did not completely inhibit induction of these cells. Furthermore, blocking endogenous IFN-gamma during stimulation resulted in a 2- to 4-fold increase in the frequency of IL-4p detected. These data demonstrate the novel finding that both IFN-gamma-resistant and IFN-gamma-sensitive IL-4p were present in freshly isolated T cell populations. Thus, during early in vitro culture, there were at least two types of IL-4p, both of which require IL-2. These data indirectly support a current model of Th ontogeny as defined by cytokine production patterns, and extend the model to include cytokine responsiveness.