Abstract
Cellular immunity to canine mammary tumor cells was studied by means of the leucocyte migration technique (LMT). Intact tumor cells, separated either by enzymatical or mechanical disruption, were used as antigen, and efforts were made to cultivate tumor cells in vitro. Fifteen female tumorous dogs were studied, and 12 non-tumorous mainly male dags were used as controls. Leucocytes from tumor-bearing females were mixed with own autologous or foreign homologous tumor cells, and control leucocytes were presented with cells from the same source. In addition, leucocytes from tumorous animals and controls were mixed. Animal group A comprised 8 tumor-bearing females. In this group mixtures of different cell numbers and different tumor cell/leucocyte ratios were tried. Animal group B comprised 7 tumor-bearing females, and 40 × 10(6) leucocytes from these were mixed with 2 × 10(6) antigencells, antigen-cell/leucocyte ratio 0.05. A great number of tumor cells (tumor cell/leucocyte ratio > 0.05) caused strong non-specific inhibition of leucocyte migration, but in spite of marked inhibition (< 61%) in the homologous system in animal group A, inhibition in the autologous system was found to be stronger (72.2–92.3%). In animal group B, dogs presented with own tumor cells showed marked inhibition (23.7–90.1%), while the controls showed a migration inhibition below 20%. Mixtures of homologous leucocytes showed inhibition of the same order as mixtures of control leucocytes and tumor cells. Thus evidence of cellular immunity against own canine mammary tumor cells was obtained. It proved difficult to cultivate the tumor cells for more than 2–3 passages. Some evidence of antigenic cross reactivity was obtained between 2 adenocarcinomas. Enzymatical separation of tumor cells did not seem to alter antigenic characteristics of the cell surface. Mechanical separation, however, proved to be simpler, more rapid and yielded cell suspensions largely free of debris, and is therefore recommended for further work.