NON-SPECIFIC SUPPRESSION OF ANTIGEN-INDUCED LYMPHOCYTE BLASTOGENESIS IN ONCHOCERCA-VOLVULUS INFECTION IN MAN

Abstract

Lymphocyte blastogenic responses to O. volvulus antigen (Oncho Ag), SKSD [streptokinase-streptodornase] and the mitogen PHA were tested in 3 groups of persons: light to moderately infected persons (INF); previously exposed by uninfected persons (EXP) and normal controls (NC). The exposed group showed significant responsiveness to Oncho Ag (.DELTA.ct/min = 6002 .+-. 1375), while the infected (.delta.ct/min = 943 .+-. 418) and normal control (.DELTA.ct/min = 428 .+-. 418) groups did not. The mean blastogenic response to SKSD were EXP, 8644 .+-. 5249; NC, 6039 .+-. 2880; INF, 2619 .+-. 1012. The reduced reactivity in the INF group to Oncho Ag showed a significant correlation with reactivity to SKSD (P < 0.05). To elucidate the mechanism of hyporesponsiveness in the infected group rigorous adherent cell depletion, by adherence to plastic followed by a nylon wool column, was utilized. When 20% plastic adherent cells were added back to the T cells prepared in this fashion, the mean blastogenic response to SKSD was significantly augmented (P < 0.01). The responsiveness to Oncho Ag was not significantly altered. The addition of indomethacin (1 .mu.g/ml) or autologous plasma had no significant effect on reactivity to either SKSD or Oncho Ag. There were no significant differences in the mean reactivity of the 3 groups to PHA-M (.DELTA.ct/min EXP 78,514 .+-. 12,564; INF 62,393 .+-. 14,447; NC 61,423 .+-. 4465). O. volvulus infection may be associated with decreased lymphocyte reactivity to both parasite related and unrelated antigens, and imply that the mechanism for the 2 types of hyporesponsiveness may be distinct. While a weakly adherent suppressor cell may account for non-specific hyporesponsiveness, the mechanism of parasite specific decreased reactivity remains unknown.