Differential susceptibility of fresh Trichomonas vaginalis isolates to complement in menstrual blood and cervical mucus.

Abstract

SUMMARY The ability of complement in human menstrual blood and cervical mucus to kill Trichomonas vaginalis was compared with that of complement in serum, and 95 fresh trichomonal isolates obtained from vaginal wash material were evaluated for susceptibility to complement immediately after isolation. Only serum and menstrual blood with haemolytic activity produced total cytolysis of T vaginalis. The cytolytic abilities ofthese fluids were totally inactivated by treatment with heat or edetic acid (EDTA), which confirms the role ofcomplement in cytolysis. Most The considerable lytic effect of fresh non-immune vertebrate serum on T vaginalis has been known for many years.' The factor responsible for lysis has been identified as activation of the alternative pathway of complement by T vaginalis in the absence of specific antibodies.45Investigations have shown great variability in the surface protein and carbohydrate molecules of the parasite.'6 Plasticity of the surface membrane may be an important factor influencing the susceptibility or resistance of T vaginalis to host immune factors.We performed this study to characterise further the role of complement in the lysis of fresh T vaginalis isolates, to investigate whether menstrual blood and cervical mucus have complement that can destroy the parasite in vitro, and to ascertain whether different

Clinical and Microbiological Aspects ofTrichomonas vaginalis

“…Many mechanisms are thought to be involved and include cell-to-cell adhesion (10,14,18,24,52,67,68,107), hemolysis (72,90,163,178), and the excretion of soluble factors such as extracellular proteinases (23,97,195) and CDF (98,240). The interaction of T. vaginalis with the members of the resident flora of the vagina may be an important factor as well (207), and, like many other protozoans, T. vaginalis has demonstrated many mechanisms which are used to evade the host immune system (9,11,20,78,154,243). The host-parasite relationship is very complex, and the broad range of clinical symptoms cannot likely be attributed to a single pathogenic mechanism.…”

“…T. vaginalis has taken advantage of a niche in which little complement is present. Cervical mucus is surprisingly deficient in complement (20,78). Menstrual blood represents the only source of complement available to the vagina.…”

“…Menstrual blood represents the only source of complement available to the vagina. Interestingly, its complement activity is about half that of venous blood, and about one-third of menstrual blood samples have no complement activity at all (20,78). Menstrual blood has appreciable complement-mediated cytotoxicity toward T. vaginalis, and although a reduction in parasite concentration is seen during menses, trichomonal infection persists even after menses (77).…”

Sequestration of host-CD59 as potential immune evasion strategy of Trichomonas vaginalis

“…Surface-associated CD59 offers some level of protection against complement-mediated lysis T. vaginalis organisms are sensitive to complement-mediated lysis, and proteases are known to protect parasites from complement (Demes et al, 1988;Alderete et al, 1995). We now wanted to test whether the surface-bound mouse CD59 provides trichomonads with some level of protection against human complement.…”

“…For example, some of the many proteases synthesized by T. vaginalis that are regulated by iron are known to be important in numerous aspects of the biology of the organism and are essential for host infection and survival Provenzano and Alderete, 1995;Figueroa-Angulo et al, 2012). It is known that trichomonads are sensitive to complement-mediated lysis, and high-iron-regulated cysteine proteases protect the organism from complement (Demes et al, 1988;Lehker and Alderete, 1992;Alderete et al, 1995;Figueroa-Angulo et al, 2012).…”