Abstract
The spontaneous regression of neuroblastoma (NB), the most common solid malignant tumor in childhood, is occasionally encountered in younger infants. Host immunity is considered to be related to this phenomenon. The present study was conducted to examine the kinetics of lymphocytes in tumor-bearing hosts using transplantable C1300 murine NB cell line. The cells (1×10^5) were inoculated into newborn A/J mice (within 24 hours after birth) and into adult mice (8 weeks old) . The animals were sacrificed 3 days, 1, 2, 3 and 4 weeks after tumor cell inoculation, and the subsets of murine spleen and thymus lymphocytes were quantified by flow cytometric two color analysis using the mouse monoclonal antibodies (anti-mouse L3T4, anti-mouse Lyt2, anti-mouse Thy1.2, goat anti-mouse Ig) in a direct and indirect immunofluorescence procedure. The results obtained were as follows : the immunity in C1300 NB-bearing infant mice has kept growing in low level as compared with normal control infant, but in adult mice it has kept declining with growth of the tumor. Thus it is reasonable to assume that the spontaneous regression of NB is caused by this growing immuno-potential in tumor-bearing infant.
