Kaposi's sarcoma: a byproduct of tumour rejection.

It is suggested that Kaposi's sarcoma is the result of a chronic immunological reaction between antigenically altered or transformed lymphoid cells and normal lymphocytes. In the course of this local graft-versus-host type activity, an angiogenesis factor is liberated and intense proliferation of mesenchymal and endothelial cells ensues. During the G.V.H.-like activity, an oncogenic virus is either transferred to or induced in the cells responsive to the angiogenesis factor. Thus, the stage is set for neoplastic transformation of these cells in an environment which is conducive to the progressive growth of the virally transformed vasoformative mesenchyme.