Chemoenzymatic method for the detection of cell-cell proximity interaction and isolation of tumor-specific antigen reactive t cells for immune therapy

A method for identifying antigen-reactive T cells present in a population of tissue infiltrating lymphocytes (TiILs) or circulating T cells, the method comprising

• a. providing a dendritic cell;
• b. incubating the dendritic cell with one or more antigens or a source of one or more antigens in order to prime the dendritic cell with one or more of the antigens;
• c. conjugating the dendritic cell on its cell surface with a suitable enzyme for catalyzing an interaction-dependent labeling reaction on a prey cell;
• wherein the conjugating occurs before or after incubating step (b), wherein the enzyme is a glycosyltransferase;
• d. contacting the dendritic cell after conjugating step (c) with a population of TiILs or circulating T cells, wherein the population comprises at least one antigen-reactive T cell and wherein the contacting occurs in the presence of a substrate for the enzyme, said substrate being a labeled donor sugar nucleotide and comprising a detectable tag;
• e. detecting any cells comprising the tag;
• thereby identifying the antigen-reactive T cells.

A method for tagging a first prey cell with a label comprising:

• contacting the first prey cell with a second bait cell in the presence of a donor sugar nucleotide that is conjugated to the label;
• i. wherein the first prey cell comprises a first cell surface glycan;
• and wherein the second bait cell comprises on its cell surface an active glycosyltransferase that is capable of catalyzing the glycosylation of the first cell surface glycan using the donor sugar nucleotide;
• ii. wherein, upon contacting the first prey cell, the second bait cell catalyzes the glycosylation of the first cell surface glycan using the donor sugar nucleotide, thereby attaching the label to the first prey cell.