A procedure for removing red cells and dead cells from lymphoid cell suspensions.

A procedure is described for simultaneously removing red cells and dead cells from lymphoid cell suspensions, based on the observation that when populations of lymphoid cells are centrifuged on a mixture of Isopaque/Ficoll, dead cells and red cells sediment whereas viable cells float. The technique very efficiently removed red cells from a wide range of lymphoid cell suspensions and eliminated lymphocytes killed by mechanical stress, by antibody and complement and by prolonged tissue culture. The depletion of red cells was greater than 99% and the recovery of viable lymphocytes usually greater than 90%, the resulting cell suspensions being around 95-100% viable. The immunological activity of B cells, helper T cells and cytotoxic T cells virtually unimpaired by the separation procedure.