A method for producing a composition of engineered cells, the method comprising: (a) incubating, under stimulating conditions, an input composition comprising T cells enriched for CD4+ primary human T cells, said stimulating conditions comprising the presence of: (i) a stimulatory reagent, wherein the stimulatory reagent comprises a primary agent that specifically binds to a member of a TCR complex, and further comprises a secondary agent that specifically binds to a T cell costimulatory molecule; and (ii) cytokines comprising recombinant human IL-2, IL-7, and IL-15, and (iii) one or more antioxidants; thereby generating a stimulated composition; wherein the input composition comprises greater than or greater than about 70%, greater than or greater than about 75%, greater than or greater than about 80%, greater than or greater than about 85%, greater than or greater than about 90%, greater than or greater than about 95% or greater than or greater than about 98% CD4+ primary human T cells; and/or the input composition consists essentially of CD4+ primary human T cells; (b) introducing a recombinant receptor into the stimulated composition, thereby generating an engineered composition comprising engineered T cells; and (c) cultivating the engineered composition under conditions to promote proliferation or expansion of the engineered cells, thereby producing an output composition comprising the engineered T cells, and wherein: the cultivating is carried out in the presence of cytokines comprising recombinant human IL-2, IL-7, and IL15; the cultivating is carried out in the present of a surfactant; at least a portion of the cultivating is performed with perfusion; and the cultivating is performed at least until the output composition comprises a threshold number of T cells. (a) incubating, under stimulating conditions, an input composition comprising T cells enriched for CD4+ primary human T cells, said stimulating conditions comprising the presence of: (i) a stimulatory reagent, wherein the stimulatory reagent comprises a primary agent that specifically binds to a member of a TCR complex, and further comprises a secondary agent that specifically binds to a T cell costimulatory molecule; and (ii) cytokines comprising recombinant human IL-2, IL-7, and IL-15, and (iii) one or more antioxidants; thereby generating a stimulated composition; wherein the input composition comprises greater than or greater than about 70%, greater than or greater than about 75%, greater than or greater than about 80%, greater than or greater than about 85%, greater than or greater than about 90%, greater than or greater than about 95% or greater than or greater than about 98% CD4+ primary human T cells; and/or the input composition consists essentially of CD4+ primary human T cells; (i) a stimulatory reagent, wherein the stimulatory reagent comprises a primary agent that specifically binds to a member of a TCR complex, and further comprises a secondary agent that specifically binds to a T cell costimulatory molecule; and (ii) cytokines comprising recombinant human IL-2, IL-7, and IL-15, and (iii) one or more antioxidants; (b) introducing a recombinant receptor into the stimulated composition, thereby generating an engineered composition comprising engineered T cells; and (c) cultivating the engineered composition under conditions to promote proliferation or expansion of the engineered cells, thereby producing an output composition comprising the engineered T cells, and wherein: the cultivating is carried out in the presence of cytokines comprising recombinant human IL-2, IL-7, and IL15; the cultivating is carried out in the present of a surfactant; at least a portion of the cultivating is performed with perfusion; and the cultivating is performed at least until the output composition comprises a threshold number of T cells. the cultivating is carried out in the presence of cytokines comprising recombinant human IL-2, IL-7, and IL15; the cultivating is carried out in the present of a surfactant; at least a portion of the cultivating is performed with perfusion; and the cultivating is performed at least until the output composition comprises a threshold number of T cells.