“…The distinction between human IL 1 and IL 2 is particularly interesting as they may be similar in size and charge, and possess similar stimulatory activities in a number of murine assay systems. It appears likely that the factors obtained from human adherent, peripheral blood lymphocytes with LAF activity (Lachman et al 1977, Togawa et al 1979), costimulator and helper T cell-replacing activity (Koopman et al 1977, and B cell-activating factor (Wood et al 1976, Wood 1977Wood and Cameron, 1978) are, in fact, due to the presence of IL L However, the formal delineation of human IL 1 and IL 2 activities in these assay systems remains to be demonstrated.…”