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Xenoantibody production directed at a wide variety of T lymphocyte-dependent and T lymphocyte-independent xenoantigens remains the major immunologic obstacle for successful xenotransplantation. The B lymphocyte subpopulations and their helper factors, involved in T-cell-independent xenoantibody production are only partially understood, and their identification will contribute to the clinical applicability of xenotransplantation. Here we show, using models involving T-cell-deficient athymic recipient mice, that rapidly induced, T-cell-independent xenoantibody production is mediated by marginal zone B lymphocytes and requires help from natural killer (NK) cells. This collaboration neither required NK-cell-mediated IFN-gamma production, nor NK-cell-mediated cytolytic killing of xenogeneic target cells. The T-cell-independent IgM xenoantibody response could be partially suppressed by CD40L blockade.

The clinical features of inflammatory pseudotumour of lymph nodes, a distinct non-malignant histopathological entity firstly described in 1988, are summarized based upon a detailed analysis of 4 personal cases and 47 cases reported in the literature. The mean age of the patients is 38 years (range 8 to 82 years) and there is no gender predilection. One third present with asymptomatic lymphadenopathy and 47% present with fever, nearly all meeting the criteria of fever of unknown origin. Abdominal complaints are occasionally present. Intermittence of symptoms is common. Hepatosplenomegaly is unusual. All lymph node areas may be involved but abnormalities are mostly confined to one or two anatomic regions. No extranodal involvement has been reported although inflammatory pseudotumour may occur in several organs with similar morphological features and identical signs of inflammations. Routine blood tests are normal except for signs of inflammation. The lesions are Gallium-avid. Diagnosis is based upon typical histopathological features. The prognosis is favorable and surgical resection frequently leads to cure. Spontaneous resolution of symptoms has been reported and nonsteroidal anti-inflammatory drugs may suppress the clinical manifestations.