Mitogenic property of a known sequence polymer, poly(Tyr-Glu-Ala-Gly)

Enhanced proliferation of murine T cell lines following interaction of poly(Glu60,Phe40) (GPhe) and antigen-presenting accessory cells. I. GPhe-stimulated enhancement of antigen-dependent proliferative responses

Following interaction of the random polymer (Glu60,Phe40)n (GPhe) with antigen-presenting accessory cells (APC), unusual costimulatory activities were noted in several murine T cell systems. When GPhe, in contrast with other random copolymers (GT,GL), was added during "inhibition" and T cell "repertoire" studies as a (negative) control to GLA-reactive nonclonal T cell lines of haplotypes H-2d (DCL-2) or H-2bm12, augmentation of T cell proliferation ([3H]thymidine incorporation ([3HT]) to homologous antigen was observed. Augmentation by GPhe was also observed in the response of a GLPhe-reactive (H-2s X H-2d)F1 T cell line and the allogeneic response of the clonal T cell line D10.G4.1. This augmentation was critically dependent on the concentration of adherent accessory cells. Although the mechanism of action of GPhe remains, as yet, undefined, the GPhe-mediated enhancement of DCL-2 (a TH2, H-2d anti-GLA, T cell line) proliferation was not dependent upon the production of either IL-1 or IL-6 by accessory cells. In addition, enhanced DCL-2 proliferation was not accompanied by a significant increase in detectable IL-4 release.

Murine Gc globulin binds to a synthetic sequential polypeptide that is a murine B lymphocyte mitogen

A non-immunoglobulin component in mouse serum was found to compete with antibody for the binding of a polyanionic antigen, poly (Tyr-Glu-Ala-Gly). The percent of the polymer (44 ng/ml) bound at physiological pH by the serum component in normal mouse serum was low (18%), but was much higher at pH 6.0 (85%). As a result, the binding of the polyanionic peptide antigen by antibody in immune serum was considerably lower at pH 6.0 than it was at physiological pH. These results should be taken into account when dealing with similar antigens that have been frequently studied in immunology, such as poly (Glu60 Ala40) and poly (Glu60 Ala30 Tyr10). The non-immunoglobulin serum component has been identified as Gc globulin, a vitamin D-binding protein that has been shown to be present on the surface of B lymphocytes. This binding might be responsible for the murine B cell mitogenicity of poly (Tyr-Glu-Ala-Gly) that has been previously reported.

Fine specificities of the murine T cell responses to (Glu Lys Ala) terpolymers

The T cell proliferative responses to GLA terpolymers among mice of H-2 a, b, d, k, q, r and s haplotypes are heterogeneous. Following immunization with GLA20, GLA40 and GLA60, mouse T cells reacted well with the three terpolymers. The cross-reactions of the above T cells to GLA5 decreased as the alanine content in the terpolymers (immunogens) increased, whereas the trend of the cross-reactions to GA40 did not change. The RIII strain showed no cross-reaction with GLA5. Only mice of H-2 haplotypes q and s failed to show cross-reactions to GA40. Mice of the H-2q haplotype are genetic non-responders to GA40, whereas those of the H-2s haplotype are responders. Immunization of SJL mice with GA40 mixed with GLA40 led to reduction of the specific T cell response to GA40. This reduction of GA40 specific T cell responses in SJL mice by GLA40 occurred during the early stage of the immune response. The kinetic study showed that it was necessary to inject the GLA40 intraperitoneally at least 7 days before GA40 in order for the reduction to take place. The PETLES and lymph node T cells from DBA/1 mice were found to respond to GLA40 differently, and these cells from SJL mice responded differently to GA40.