Immunosuppression is a common reason for drug withdrawal from the market. The traditional immune function test used to estimate materials’ immunosuppression is T cell dependent antibody response (TDAR). This method involves a 28 day, in vivo, study evaluating animal antibody titers to a known antigen (KLH) with and without challenge. Due to the limited quantities of novel drug candidates, an in vitro method called Human Leukocyte activation (HuLa) has been developed as a substitute to the traditional TDAR assay in early preclinical development. The method presented herein is based on the HuLa assay originally developed by Mark Collinge et al at Pfizer . The protocol presented in this document has been adapted for use with engineered nanomaterials.