Electrokinetic Properties and Mitogen Responsiveness of Mouse Splenic B and T Lymphocytes Following Hydrocortisone Treatment

Abstract

CBA mice recieved a single intraperitoneal injection of hydrocortisone acetate (OHC) in a dose of 125 mg/kg body weight. At various times therafter, electrophoretic mobility (EPM), surface immunoglobulin (SIG) and in vitro DNA synthetic reactivity to concanavalin A (ConA), phytohemagglutinin (PHA), lipopolysaccharide (LPS) and tuberculin (PPD) were investigated on splenic lymphocytes. OHC was found to deplete rapidly the spleen to a minimum of 18% of control cellularity by day 4 posttreatment. At this time, the proportions of low mobility (LM) and SIG-bearing lymphocytes (B cells) were reduced respectively to 28% (control 54%) and 20% (control 45%). The proportion of high mobility (HM) lymphocytes (T cells) was increased to 72% (control 45%). While the mean EPM of LM cells (0.71) was only slightly and transiently reduced, that of HM cells was significantly augmented (1.24) over control value (1.16). This latter finding was interpreted as indicating the selective removal by OHC of a T cell subpopulation with a mean EPM around 1.10. Changes in mitogenic responsiveness were consistent with these alterations of B and T cell compartments. Despite a marked drop in spontaneous 3H-thymidine uptake, the absolute response to T cell mitogens ConA and PHA remained relatively unchanged. By contrast, the reactivity to B cell mitogens LPS and PPD was strongly depressed. Starting by day 12, regeneration and normalizaiton of lymphocyte populations proceeded slowly and were not achieved before day 26-34.