In vitro and in vivo studies of the target cell for dialyzable leukocyte extracts : Evidence for recipient specificity

Abstract

The effects of dialyzable leukocyte extracts (DLE), assumed to contain the so-called “dialyzable transfer factor,” were tested in vivo and in vitro. In vivo, DLE was used to treat a patient with an apparent monocyte deficiency, before and after treatment with supernatants of buffy-coat cells from normal individuals. In vitro, white blood cells from the same patient and from normal controls were used as target cells for DNA synthesis assays. The normal cells were either cells isolated on a Ficoll-Isopaque gradient (FC) or FC that were nonadherent to cotton after incubation for 45 min at 37°C (NAC). These cells were tested (a) in the presence or absence of DLE and in the presence or absence of antigens to which the donors of the DLE batches were sensitive; (b) in the presence or absence of DLE or antigen, with supernatants from cultures of normal FC (SFC); (c) in the presence or absence of DLE or antigen, with supernatants from nonadherent cells alone (SNAC). DLE was also tested in vitro in a leukocyte migration inhibition factor (LIF) assay with and without antimonocyte serum added to the system. The results, both in vivo and in vitro, suggest that normal adherent cells or a factor(s) released by these cells is required for the effects of DLE. The importance of considering the condition of the patient (recipient specificity) in any theoretical attempt to explain the mechanism and possible specificity of action of DLE is discussed.