Kinetics of the graft versus host reaction during allogeneic tumour enhancement

An experimental model has been devised which conditions for tumour enhancement, in which an AKR lymphoma (L15) inoculated within a glass cylinder (GC) implanted under the skin of BALB mice leads to the development of an allogenic lymphoma which kills 55% of the animals in an average of 37 days; L 15 implanted s.c. does not grow in BALB mice. In order to compare the T lymphocyte response of BALB mice inoculated with L 15 by the s.c. and the GC route, the capacity of their spleen cells to induce a graft versus host (GvH) reaction was determined in F 1 (BALB X AKR) on day 0, 3, 10, 14 and 31 after tumour challenge. The kinetics of the GvH reaction followed opposite trends: while the s.c. route led to a very gradual increase, the GC route yielded early high values which gradually decreased to minimum in tumour-bearing animals on day 31. On that day, the animals which had rejected the tumour, by either route, yielded high GvH values. The sole inoculation of acellular tumour extracts (AE L 15), without tumour challenge, also led to a high GvH response. The GvH reaction carried out in F1 (BALB X C57B1/Ks) only gave a positive response in the animals inoculated by the GC route, suggesting that minor histo-compatibility antigens are involved in the early response characteristic of this group. It is concluded that allogeneic tumour enhancement in this model, is accompanied by a marked and early stimulation of T cells, contrasting with the late response obtained in animals rejecting the tumour.