[Disorders of B cell activation in splenectomized patients]

Using a reverse hemolytic plaque assay as the effector system, we studied in vitro B-lymphocyte function in 12 patients after posttraumatic splenectomy as well as in 25 normal individuals. The time interval between the splenectomy and the immunological studies varied between 2 days and 7 years. Compared to normal individuals, the splenectomized patients had markedly elevated numbers of spontaneous immunoglobulin-secreting cells and severely decreased responses to the polyclonal activator pokeweed mitogen, indicating an in vivo polyclonal B-cell activation. A tendency towards normalization of these abnormalities, especially the high spontaneous ISC levels, could be observed during the time interval extending up to 7 years after splenectomy. In order to characterize the mechanism responsible for the altered immune response in splenectomized patients, in vitro experiments were performed with separated lymphocytes. These revealed an impaired T-helper cell capacity as well as an intrinsic B-cell defect. Marker analysis with monoclonal antibodies revealed normal proportions with the exception of OKT 4 positive and B 1 positive cells that identify T-helper/inducer and peripheral B-cells, respectively. We conclude that immune dysfunction in peripheral blood lymphocytes of splenectomized patients involves mainly the OKT 4 positive cell population.