Differential effects of poly (Glu60, Phe40) (GPhe) on murine TH1 and TH2 cells

The random amino acid copolymer (Glu60, Phe40)n (GPhe) was previously shown to augment antigen-dependent proliferation of the murine TH2 cell lines DCL-2 and D10.G4.1. In the present study, the addition of GPhe to (Glu36, Lys24, Ala40)n (GLA)-primed BALB/c primary lymph node (1 degree LN) T cell cultures, the source of DCL-2, resulted in significant suppression of both the proliferative and lymphokine response to GLA. Suppression by GPhe of the 1 degree LN response was subsequently shown to be neither antigen- nor haplotype restricted, and was inhibitable by polyclonal anti-GPhe antibodies. Studies were extended to a GLA-reactive T cell hybridoma clone (DL.4G6.1). where significant suppression by GPhe of GLA-stimulated lymphokine production was observed as measured by markedly decreased HT-2 stimulatory activity of the collected supernatants. Subsequent antibody blocking experiments employing the monoclonal anti-murine IL-4 antibody 11B11 revealed that BALB/c GLA-reactive 1 degree LN T cells and DL.4G6.1 did not produce detectable levels of IL-4 in their culture fluids when stimulated by GLA, which suggested that these cells, unlike DCL-2, were TH1-like in nature. The addition of GPhe to the TH1 clones 5.2 and 5.9 resulted in significant suppression of proliferation to homologous antigen (ovalbumin), in contrast to the augmentation observed with the TH2 cell lines DCL-2 and D10.G4.1. It was concluded from these data, that the addition of GPhe to various T cell cultures lead to unusual suppressive and augmenting activities specific for TH1 and TH2 cells, respectively. Although the mechanism for these dichotomous effects of GPhe is as yet undetermined, several possibilities are considered.