Abrogation of suppression of delayed hypersensitivity induced by Candida albicans-derived mannan by treatment with monophosphoryl lipid A

Abstract

Monophosphoryl lipid A (MIA), derived either from SalmoneUa minnesota or SalmoneUla typhimurium, was tested for its ability to alter Candida albicans mannan (MAN)-specific suppression. Since we showed previously that naive mice injected intravenously (i.v.) with MAN developed suppressor T cells capable of down-regulating delayed-type hypersensitivity when transferred to immunized recipients, MLA was tested for its ability to influence suppressor activity in the donors of suppressor cells. T-lymphocyte-enriched suspensions from donor mice treated with MLA, especially that derived from S. typhimurium, 2 or 3 days after the injection of MAN lost the ability to suppress delayed-type hypersensitivity when transferred to immunized mice. Transferable suppressor activity was reduced but not always completely abrogated when donor animals were treated with MLA 1 day following the administration of MAN. In several experiments, S. minnesota MLA also abrogated activity, but it was not effective in other transfer experiments. In a different type of experiment, MLA was given to immunized mice which had been suppressed directly with MAN. Mice were immunized, either by the introduction of C. albicans intragastrically followed by inoculation intradermally (i.d.) or by two i.d. inoculations, and MAN-specific suppressor cells were induced in such animals by the i.v. injection of MAN 1 day before the first or second i.d. inoculation in animals given intragastric plus i.d. inoculations and those given two i.d. inoculations, respectively. MLA was administered to such mice prior to the i.v. injection of MAN, on the same day, or 1 to 4 days thereafter. S. typhimurium MLA, especially when given to mice 2 days following the administration of MAN, caused a partial abrogation of suppressor activity. Overall, however, MLA, at 5 to 100 ,ug, had variable and minimal effects on suppressor activity in immunized mice suppressed by the i.v. administration of MAN. In summary, MLA is clearly capable of abrogating MAN-induced suppression when given to nonimmunized animals in which MAN-specific suppressor cells had been induced, but its efficacy in immunized animals suppressed by the i.v. administration of MAN was marginal.

Alterations in Frequency of Interleukin-2 (IL-2)-, Gamma Interferon-, or IL-4-Secreting Splenocytes Induced byCandida albicansMannan and/or Monophosphoryl Lipid A

“…MPL from Salmonella typhimurium was a gift from Ribi ImmunoChem Research, Inc. (Hamilton, Mont.). It was prepared for injection into animals as described previously (14). Fifty micrograms of MPL was injected intraperitoneally (i.p.)…”

“…at selected times prior to sacrifice. The quantity of MPL and the timing of the injections were based on previous studies (14). To induce the production of MAN-specific downregulatory cells, 500 g of MAN dissolved in nonpyrogenic saline (NPS; McGaw, Inc., Irvine, Calif.) was administered intravenously (i.v.)…”

“…to mice via the lateral tail vein at various times prior to sacrifice. The quantity of MAN and the timing of its administration with respect to MPL and the development of MAN-specific downregulatory cells were based on previous studies (14,18).…”

“…In the past we demonstrated that MPL abrogated the downregulatory activity exerted by CD8 ϩ cells if donor MAN-treated mice were given MPL in vivo 48 to 72 h prior to sacrifice (14). Moreover, if splenocytes taken from MAN-treated mice were incubated with MPL in vitro prior to transfer of such cells to immunized mice, the ability to downregulate DH was lost as well (12).…”

“…In addition to demonstrating the phenotype of the inducer and effector cells in the MAN-specific pathways, we have determined that the downregulatory activity of the effector cell could be abrogated by in vivo treatment of animals with monophosphoryl lipid A (MPL) (14) or by in vitro treatment of effector cell suspensions with MPL prior to transfer to immunized recipients (12). The in vitro incubation requires very small amounts of MPL to be effective, and the incubation time is short and at low temperature, 30 min at 4°C.…”