Inhibition of human lymphoproliferative responses and altered lymphocyte membrane phenotype by succinylacetone.

Succinylacetone (SA) proved to be a potent inhibitor of in vitro lymphoproliferative responses. This compound (3.0 mM) reduced the incorporation of 3HTdr by > 90% in mononuclear cell cultures stimulated with PHA, anti-CD3, IL-2 or phorbol dibutyrate-Ca2+ ionomycin.

Thymosin alpha 1 modulates the expression of high affinity interleukin-2 receptors on normal human lymphocytes.

In this report we demonstrate that thymosin alpha 1 (T alpha 1), a synthetic peptide composed of 28 amino acid residues, and thymosin fraction 5 (TF5) enhance the number of high affinity interleukin 2 receptors (IL-2R) expressed by human peripheral blood lymphocytes in response to in vitro stimulation with phytohemagglutinin (PHA). Thymosins did not, however, alter the affinity of the IL-2R for its ligand. Dose-response studies using a wide range of concentrations indicated a bimodal distribution of responsiveness to T alpha 1.

Lyme disease spirochetes induce human and murine interleukin 1 production.

IL 1 is a major immunoregulatory molecule produced by macrophages, and it appears to be the molecular orchestrator of nonspecific host defense mechanisms against a variety of environmental insults. Many investigators have used artificial agents to stimulate macrophages to produce IL 1. We now report production of large quantities of IL 1 after a physiologic stimulus.

The effect of age on the infection and immunoresponsiveness of mice to Babesia microti.

5he effect of age on the immunological responses to Babesia microti infection in the mouse was investigated. Aged mice experienced reduced and delayed peak parasitemias compared to younger animals; however, the old mice failed to clear the parasites from the blood and experienced fluctuating parasitemias until death. Babesiosis produced suppression of responses to nonspecific B and T cell mitogens concomitant with rising autoantibody plaque forming cells reactive with untreated and bromelain modified mouse erythrocytes.