The present disclosure provides a fusion polypeptide comprising a mutant PD-L1 immunoregulatory polypeptide and a mutant immunomodulatory peptide. The present disclosure provides T cell regulatory multimeric polypeptides and compositions comprising the same, and T cell regulatory multimeric polypeptides include the mutant immunomodulatory polypeptides of the present disclosure. The present disclosure provides a nucleic acid comprising a nucleotide sequence encoding a T cell regulatory multimeric polypeptide and a host cell comprising the nucleic acid. The present disclosure provides a method of modulating the activity of a T cell, the method comprising contacting the T cell with a T cell modulating multimeric polypeptide of the present disclosure.本開示は、変異PD-L1免疫調節ポリペプチド及び変異免疫調節ペプチドを含む融合ポリペプチドを提供する。本開示は、T細胞調節多量体ポリペプチド及びこれを含む組成物を提供し、T細胞調節多量体ポリペプチドは、本開示の変異免疫調節ポリペプチドを含む。本開示は、T細胞調節多量体ポリペプチドをコードするヌクレオチド配列を含む核酸及びこの核酸を含む宿主細胞を提供する。本開示は、T細胞の活性を調節する方法を提供し、この方法は、T細胞を本開示のT細胞調節多量体ポリペプチドと接触させることを含む。