The effect of various types of splenectomy on the development of B-16 melanoma in mice

260 CB57BL/J6 mice were used in an experimental protocol designed to invest igate the effects of 4 different varieties of splenectomy on the growth rat e of subcutaneously implanted GB-16 melanoma. In addition, the mean and abs olute survival of the mice, the histopathology of the tumour and the effect s of the same procedures on the immunological status of the tumour-bearing animals as assessed by serum IgG levels and immunoelectrophoresis were dete rmined. The effects of the timing of the splenectomy and the removal of the primary tumour after splenectomy on the above parameters were also annotat ed. The following were found: First, splenectomy performed 1 week after B-1 6 melanoma tumour implantation in mice i.e. in the early period of oncogene sis, lengthened the survival of the grafted experiments, delayed tumour gro wth, reduced the "activity" of the tumour and caused pseudoencapsulation of the tumour by fibrous tissue. It increased, but not by a statistically sig nificant degree (p>0.05), the circulating levels of the IgG immunoglobulin. Second, splenectomy performed 4 weeks prior to grafting of the same tumour did not affect the circulating IgG levels, nor did it prolong survival; ho wever, it reduced the rate of tumour growth and pseudoencapsulation of the tumour was observed. Third, splenectomy at the early stages of oncogenesis in combination with surgical removal of the primary tumour increased absolu te and mean survival, delayed the tumour growth rate, increased the time to relapse and reduced the "activity" of the pseudocapsulated tumour.