Whipple's disease: a review emphasizing immunology and microbiology.

Whipple's disease is an important and fascinating problem of local immunity in the gastrointestinal tract. Does the disease occur when an organism that is rare in nature infects an individual or do patients with Whipple's disease have a definable defect in their immune response that permits infection by a more common agent? Data in recent years indicate that there is only one type of microorganism that causes Whipple's disease. It is rod-shaped by electron microscopy and has a definable antigenic pattern by immunofluorescence. Paradoxically (considering its geometry), it reacts most strongly with antisera directed to streptococcal antigens. Patients with Whipple's disease do not have a disorder of immunoglobulin synthesis and do not have immune complexes present in their gut walls. Further, although earlier studies indicated that a defective response of T-lymphocytes to PHA is consistently present in these patients even years after therapy, more recent studies have found no consistent defect in mitogenic responses to PHA, CON A, or PWM. Also, recent studies indicate that mononuclear cells from patients with Whipple's disease usually mediate antibody-dependent cell-mediated cytotoxicity as well as controls, although spontaneous cell-mediated killing may be decreased. All these studies suggest that the defect is not primarily of lymphocytes, rather it is more likely that a defect exists in monocytes and macrophages. Future studies on Whipple's disease should add to existing knowledge of how the immune processes intracellular microorganisms.