Altered immune response (humoral and delayed-type hypersensitivity reactions) to sheep red blood cells in the course of experimental filarial infections (Litomosoides carinii, Brugia malayi, Acanthocheilonema viteae) ofMastomys natalensis

Abstract

Litomosoides carinii-, Acanthocheilonema viteae- or Brugia malayi-infected Mastomys natalensis were sensitised against sheep red blood cells (SRBC) on various occasions after infection to determine the effect of filarial infections on the immune response to a non-filarial antigen. The phagocytic activity of the reticuloendothelial system (RES) was controlled in vivo by the elimination of 51Cr-labelled SRBC. Antibody titres against SRBC (agglutinating and lytic antibodies) were similar to those of uninfected controls in L. carinii- or B. malayi-infected Mastomys sensitised during prepatency or early patency up to 90 days post infection (p.i.) but were reduced in animals sensitised during patency. A significant inverse correlation existed between anti-SRBC antibody titres and microfilaraemia levels. In contrast, A. viteae-infected Mastomys showed reduced humoral anti-SRBC responses at the end of prepatency, whereas the response tended towards normal with increasing parasitaemia. Delayed-type hypersensitivity (DTH) against SRBC was measured as footpad swelling after sensitisation by the s.c. or i.v. route and intraplantar challenge. DTH reactions were reduced during prepatency in all infections after s.c. sensitisation. During patency, 24-h reactions were similar to those of age-matched controls but the swelling persisted 24 or 48 h longer than in the latter. In A. viteae infections, even enhanced 24-h reactions were found during patency. Histological investigations did not reveal differences in the type of cell infiltrations between infected and control animals. After i.v. sensitisation with SRBC, L. carinii- and A. viteae-infected animals showed weaker DTH reactions than the controls, independent of the period after infection. In the case of B. malayi infections, DTH reactions were similar to those of controls during early prepatency, whereas reduced DTH responses were observed later than 50 days p.i. As shown in L. carinii-infected animals, depressed DTH reactions after i.v. sensitisation did not depend on an altered expression phase but rather on an altered regulation during the inductive phase of the response: increases in the sensitising SRBC doses that caused decreasing DTH reactions in uninfected animals led to enhanced reactions in infected animals. Phagocytosis of i.v. injected 51Cr-labelled SRBC was enhanced during prepatency in L. carinii infection and during patency in all infections.

On the Pathogenesis of Anaemia and Leukopenia in Filarial (Litomosoides carinii) Infection of Mastomys natalensis

“…infection of man FLEMING, 1981) and experimental animals (JENNINGS et al, 1976). Thus, functionally/morphologically inadequate RBCs may reach the circulating blood but probably will be rapidly eliminated by the strongly activated MPS of these animals (see ZAHNER et al, 1989). A similar situation was reported on T. corrplense infected Mastomys by OJOK (1984).…”

“…This then would suggest an increased RBC turnover rate in these animals. A reason may be seen in RBC degradation by an enhanced phagocytic activity of the mononuclear phagocytic system (MI'S) in infected animals as it was shown recently (ZAHNER et al, 1989). Generally supportive factors in RBC elimination could be furthermore an absorption of metabolic filarial antigens to RBC resulting in immune elimination of such cells as described in Trypanosoma spp.…”

Immunomodulatory effects in Litomosoides sigmodontis -infected Mastomys coucha

“…Thus, the modulatory eect of L. sigmodontis on the cellular responses of the host seems to be more complex than it appears on the basis of the time course of cellular reactivity to mitogens. The reader is also referred to a previous study on the in vivo cellular response of L. sigmodontis-infected animals to sheep red blood cells (SRBC) as ®laria-unrelated antigens (Zahner et al 1989), which, apart from a generally suppressed response, likewise indicated very complicated regulation processes. It may be that a situation takes place in L. sigmodontis-infected M. coucha that is similar to that recently described by Allen et al (1996) in mice implanted with adult B. malayi.…”

Effect of chemotherapeutic treatment on cytokine (IFN-γ, IL-2, IL-4, IL-5, IL-10) gene transcription in response to specific antigens in Brugia malayi-infected Mastomys coucha

“…malayi system which is immunologically well determined (e.g., see Zahner et al , 1989Zahner and Rudolph 1987;Lutsch et al 1987;Schares and Zahner 1994) under two aspects. First, in a time course study over 230 days p. i., we determined antigen-driven transcription of various cytokine (IFN-γ, IL-2, IL-4, IL-5, IL-10) genes in peripheral blood mononuclear cells using specific antigens derived from L 3 , adult males, females, and microfilariae and employing a semiquantitive reversetranscription polymerase chain reaction (RT-PCR).…”