Abstract: Methods and systems for determining a viscosity of liquid samples are provided. The methods and systems utilize an acoustic liquid handler. The acoustic liquid handler has a first location adapted to receive a liquid sample. The acoustic liquid handler is configured to apply one or more acoustic signals to the liquid sample in the first location until a specified amount of the liquid sample has been transferred from the first location to a second location of the acoustic liquid handler. The acoustic liquid handler has a controller configured to determine the viscosity of the liquid sample based on a number of acoustic signals required to transfer the specified amount of the liquid sample from the first location to the second location.

Abstract: Provided herein are IL-2 muteins and IL-2 mutein Fc fusion molecules that preferentially expand and activate cells and are amenable to large scale production. Also provided herein are methods of making and using the compositions of the present invention.