The introduction of one or two 3β‐cholestanyl residues into benzylpenicilloyl‐eicosa‐L‐lysines greatly potentiates their tolerogenicity for anti‐benzylpenicillol IgE antibody formation

Abstract

BALB/c mice were repeatedly immunized with microgram doses of benzylpenicilloylated Ascaris protein(s) (BPO9Asc) in alum. At different stages of the immune response, BPO21 eicosa-L-lysine or two analogs containing one or two hydrophobic p-oxymethylbenzyl-3 beta-cholestanyl succinate (OSuco) groups were injected. When injected early in the immune response, the anti-BPO IgE antibody formation was much more strongly and permanently suppressed by the lipophilic conjugates than by the hydrophilic BPO21 eicosa-L-lysine. A similar, but less marked, suppressive effect was observed on the anti-BPO IgG1 response. By adoptive cell transfer experiments, it was found that the OSuco-containing derivatives induce and act via suppressor T lymphocytes, since this cell-mediated suppression was sensitive to cyclophosphamide or to treatment with anti-Lyt-2.2 antibody plus complement. When these compounds were injected into repeatedly immunized mice producing late ongoing antibody responses no differences in suppression between hydrophilic and hydrophobic derivatives were observed. In this case, the IgE response was suppressed by about 50%, while the IgG1 response was not affected. These results are compatible with the suggestion that early IgE responses are most sensitive to T cell-mediated suppression and that T suppressor cells are better induced by lipophilic than by hydrophilic antigens. The late ongoing IgE response, on the other hand, is less amenable to T cell-induced suppression and tolerogenic effects brought about by plurivalent BPO antigens operate directly on hapten-specific IgE-bearing B cells, regardless of their lipophilic character.

Macrophages pulsed with sterol‐conjugated benzylpenicilloylated eicosa‐lysine induce T cell‐mediated suppression of IgE antibody formation in mice

“…The anti-KLH IgE titers of all groups were equal and increased in parallel following booster immunizations (data not shown), suggesting that the observed anti-BPO suppressions were antigen specific. This observation is in agreement with the previous finding according to which BP02oLys~(OSuc0)~ when injected into naive or immunized mice induced hapten-specific suppression of the IgE antibody response [5]. The total anti-BPO antibody titers of the same sera showed no significant differences among the various groups of Fig.…”

“…I found that peritoneal macrophages pulsed with B P 0 2 0 L y~~0 ( O S~~o ) 2 , but not with its hydrophilic analog BP021Lys20-OH effectively suppressed de novo as well as ongoing IgE antibody formation in vivo. It was previously shown that high doses (3 x 1 mg) of BPOzoLyszo (OSUCO)~ induced strong IgE suppression in vivo [5]. We therefore investigated whether the observed IgE suppressions were merely due to carryover of tolerogen by the transferred cells.…”

“…This may be decisive for their increased uptake by the strongly phagocytic macrophages (Fig. 5 , [5]). Antigen uptake by macrophages is a metabolically active process [20], which is initiated by binding to membrane receptors [24].…”

“…Adherent cells pulsed with 75 pl/ml BPOzoLys~o(OSuco)z or 300 pg/ml the Ly-2.2 surface marker [22]. We previously showed [5] Lipid modification of antigens leads to highly amphipathic structures which tend to form large and stable micelles in aqueous media [ l l , 231. This may be decisive for their increased uptake by the strongly phagocytic macrophages (Fig.…”

“…The adoptive transfer of SC from primed and/or tolerized animals into cyclophosphamide-pretreated recipients was performed as previously described [5]. In brief, primed SC (pSC) were obtained from BALB/c mice which had been immunized with BP03KLH (10 pg) in alum (2 mg) 2 weeks previously.…”