Use of antibodies for enrichment of engineered t cells with exogenous immune receptors and antibodies for use in depletion of engineered t cells

A pharmaceutical composition comprising:

• a T cell mixture comprising:
• engineered T cells comprising at least one exogenous receptor;
• and
• non-engineered T cells with endogenous alpha beta T cell receptors,
• wherein said pharmaceutical composition exhibits a low allo-reactivity that is achieved by contacting said mixture with an amount of an antibody that specifically binds to the endogenous alpha beta T cell receptor, wherein said amount is sufficient to reduce the allo-reactivity of the composition as compared to a corresponding composition wherein the T cell mixture is not contacted with said antibody.

A method of treating cancer in a subject comprising:

• providing to said subject a pharmaceutical composition comprising
• engineered T cells with exogenous immune receptors;
• and
• non-engineered T cells with endogenous alpha beta T cell receptors,
• wherein said pharmaceutical composition exhibits low allo-reactivity, and
• wherein said low allo-reactivity is achieved by contacting said mixture with an amount of an antibody that specifically binds to the endogenous alpha beta T cell receptor, wherein said amount is sufficient to reduce the allo-reactivity of the composition as compared to a corresponding composition that is not contacted with said antibody.

A preparation comprising:

• engineered T cells with at least one exogenous receptor;
• and
• non-engineered T cells with endogenous alpha beta T cell receptors,
• wherein said preparation is at least two-fold enriched for said engineered T cells.