Evidence of acquired immune deficiencies in Mediterranean lymphoma. A possible aetiological link

Patients with Mediterranean lymphoma (M.L.) had a significant reduction in humoral immunity (IgG and IgM) as well as impaired cellular immunity (50% were anergic to three antigens--P.P.D., mumps, and dinitrochlorobenzene). Any hypothesis for the pathogenesis of M.L. has to account for the peculiar geographic distribution of the disease, the age and sex incidence, the plasma-cell nature of the tumours, the associated heavy plasmacytic proliferation with relatively intact intestinal mucosa, involvement of the proximal small intestine, and alpha-chain production in a large proportion of patients. All areas in which M.L. is common are currently involved in the seventh cholera pandemic. Vibrio cholerae toxin inhibits both immediate and delayed immune reaction in vitro through its effect on cyclic adenosine monophosphate. V. cholerae antigens stimulate the proliferation of IgA-producing immunocytes in the mucosa without deeply penetrating the mucosa. The proximal small bowel is usually affected by the disease but there is little epithelial damage. The population in endemic areas is continuously exposed to V. cholerae antigens and toxins. It is suggested that such exposure, under certain genetic or other circumstances, may produce a state of immunosuppression in the gut thus accelerating, predisposing to, or producing lymphoplasmacytic neoplasia.