AT122A is Click's Medium (EHAA) Eagle Hank's Amino Acids without L-glutamine and mercaptoethanol. It is commonly used to support clonal cultures of murine T cells and hybridomas. Click's medium was developed by Robert Click to study the in vitro immune response of mouse spleen cells. The addition of mercaptoethanol to the medium permits successful immunization of spleen cells with heterologous RBC cultured under stationary conditions without daily feeding.