CD4 and malaria: Some studies have reported that the freeze–thaw process can result in a three to five-fold reduction of malaria antigen-specific IFN-γ-producing CD3+CD4+ effector populations, and others have suggested that cryopreservation in general leads to increased cytokine and chemokine responses, which is expected for IFN-γ in cultured PBMC supernatants [5, 27].