Modulation of the posthemorrhage bacterial polysaccharide antigen-specific antibody response by interleukins 2 and 4.

Abnormalities in immune response play a major role in the increased susceptibility to infection after hemorrhage and trauma. Several studies have shown decreased release in vitro of interleukin-2 (IL-2) following blood loss. To better define in vivo the interactions between T and B cells, as well as the effects of treatment with the T cell-derived cytokines IL-2 and IL-4, mice were injected with concanavalin A at predetermined times posthemorrhage, and the percentages and numbers of splenic plasma cells producing antibody to the bacterial polysaccharide antigen levan (from Aerobacter levanicum) were determined. Decreased numbers and percentages of levan specific splenic plasma cells were found in animals treated with concanavalin A both immediately and 2 to 4 days after hemorrhage. Treatment in vivo with recombinant IL-2, but not IL-4 or anti-IL-2 receptor antibodies, following blood loss was able to increase the numbers of levan specific plasma cells to levels as high or higher than those found in normal, unhemorrhaged animals, but was unable to affect the decreased percentage of levan specific splenic plasma cells. These results suggest that the use in vivo of IL-2 may restore bacterial antigen specific antibody responses to normal levels after blood loss.