At one week after injection of V/I, histology showed invasion of lymphocytes
(Figure 2). In addition, there were small numbers of
macrophages, granulocytes, and apoptotic tumor cells. At the
end of the process, tumor cells had been replaced by reactive
connective tissue cells with hardly any or no tumor cells
(Figure 3). This is understandable as healing of dead tissue
(e.g. due to heart infarction) is a time-consuming process. In
the present study, the observation that tumor tissue after
some weeks is replaced by connective tissue is compatible
with such a time consuming process (25, 26).
Remarkably, in the 12 tumors that we studied, never
were there fields of necrotic cells found in the tumor.
Macrophages and granulocytes were also rare. This might
be a result of the two-week interval between the last V/I
injection and the histological examination. From studies of
heart infarction, it is well-known that the presence of
granulocytes is limited to the first two days after the event,
and necrotic tissue is rapidly replaced by young connective
tissue, usually within a week after infarction (27). A
similar process may occur in TVTs treated with V/I. In the
present study, we saw only rather late processes after V/I
injection.