Enhanced T-cell rosette formation in shigellosis by the in vitro use of thymopoietin

Abstract

The results from this study suggest that the large nul cell lymphocyte population seen in patients with Shigella dysentery, does contain a sub-population of cells that will respond in vitro to thymopoietin, a bovine thymic extract, by increased E-rosette formation. It is felt that this sub-population is in fact immature T-cells. A previous study has shown that an unusual leukaemoid reaction develops in a substantial number of patients with Shigella dysentery. The leukaemoid response was primarily granulocytic in nature but there was also a substantial increase in the mean number of lymphocytes. The proportion of the various populations of lymphocytes from leukaemoid and non-leukaemoid subjects were altered, B-cells remained constant, while the T-cells were depressed with a corresponding rise in the proportion of nul cells. The cumulative results of this and other studies demonstrate that the T-cell arm of immunity is compromised in shigellosis. Indeed the degree of compromise may ultimately be the decisive factor in determining the severity of this disease. A previous study ( Jackson et al., 1979) of the sub-populations of peripheral blood lymphocytes from patients with Shigella dysentery indicated an imbalance in the proportion of T, B, and nul cell lymphocytes. The proportion of B-cells remained constant, while the T-cells were depressed with a corresponding rise in the proportion of nul cells. It was suggested that some of these nul cells were in fact immature T-cells. To support this hypothesis peripheral blood lymphocytes from Shigella patients were incubated with a bovine thymic extract, thymopoietin, to determine if such an exposure would increase the percentage of T-cells.