The immunological capacity of peripheral lymphocytes in a blast-transformation system using frozen-stored cells.

Suspensions of isolated peripheral lymphocytes were frozen to --95degreesC using a programmed freezing apparatus and dimethyl sulphoxide as a cryoprotective agent. In comparisons among fresh cells, frozen cells, and cells stored in storage medium, freezing was found to be the best method of storage with retention of almost the same immunocapacity as fresh cells and with the same coefficients of variation for results after stimulation with phytohemagglutinin, pokeweed mitogen, concanavalin A, purified protein derivative, and allogenic cells in mixed lymphocyte cultures as was obtained with fresh cells. Blast transformation was found to be dependent on the number of cells in the cultures, the amount of [14C]thymidine added, and the amount of phytohemagglutinin used by independent of the amounts of pokeweed mitogen and concanavalin A. The maximum responses for normal lymphocytes and lymphocytes from uremic patients after stimulation with phytohemagglutinin occurred simultaneously, but after stimulation with allogenic cells maximum response was obtained earlier for "uremic" than for normal lymphocytes. It was concluded that frozen-stored lymphocytes are suitable for in vitro quantitative measurements of the cellular immune response in an immunological sequential study provided that the above mentioned factors are well defined.