Dendritic cells pulsed with keyhole limpet hemocyanin and cryopreserved maintain anti-tumor activity in a murine melanoma model

We compared viability, phenotype, in vitro function and therapeutic efficacy of murine unpulsed-dendritic cells (-DC), DC pulsed with keyhole limpet hemocyanin (KLH-DC) and cryopreserved KLH-DC (C-KLH-DC). Mean viability (% +/- SE) of unpulsed-DC, KLH-DC and C-KLH-DC was 93.6 +/- 0.9, 93.9 +/- 0.8 and 87.4 +/- 1.6, respectively. Pulsing DC with KLH did not induce maturation or affect in vitro function. Cryopreservation of KLH-DC reduced MHC 1, CD80 and CD86 expression, endocytic capacity and allogeneic splenocyte stimulatory capacity. Intratumoral (i.t.) vaccination of mice bearing s.c. D5 melanoma with unpulsed-DC, KLH-DC or C-KLH-DC elicited comparable antitumor immune responses and inhibited tumor growth to the same extent. Combining radiotherapy with i.t. unpulsed-DC, KLH-DC or C-KLH-DC administration enhanced induction of anti-tumor immune responses and inhibition of tumor growth to a similar degree. Cryopreservation of KLH-DC slightly reduces viability, expression of co-stimulatory cell surface markers and in vitro function; however, in vivo anti-tumor activity is fully maintained with or without radiotherapy. (C) 2008 Elsevier Inc. All. rights reserved.