Mediators of cellular immunity, their nature and assay.
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When sensitized leukocytes were re-exposed to EBV antigen or to tuberculin-purified protein derivatives, they produced lymphokines, including the migration inhibition factor, which inhibited the migration of guinea-pig peritoneal exudate cells, and other lymphokines with the characteristics of interferon, which inhibited EBV-induced transformation and EBV superinfection of target cells. Unsensitized leucocytes from sero-negative adults and from neonates did not produce lymphokines when challenged with the antigens. This indicates that cell-mediated immunity and its associated soluble mediators may be involved in the control of EBV infection and that the interferon release assay is a useful in vitro correlate for the study of cellular immunity to EBV.
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Eight hundred and eighty patients hospitalized in a geriatric hospital were routinely tested with 2, 10, 30 and 100 i.u. tuberculin. Among these, fifty-four patients were selected on the basis of negative skin tests and absence of evident diseases interfering with the function of the immune apparatus. A battery of tests analysing cell-mediated immunity was applied to those fifty-four patients. It appears that elderly patients having a negative test to 100 i.u. tuberculin show very infrequent sensitization to three other thymus-dependent antigens. The capacity of this selected population to become sensitized to DNCB is poor (20%). Furthermore they exhibit a low per cent of peripheral blood T cells (36%) and a poor capacity to respond in vitro to mitogens such as PHA. Testing the in vitro response to a battery of antigens demonstrates a good correlation with the results of the skin tests. Finally the leucocytes of 25% of this selected population failed to produce LIF in vitro in the presence of PHA. These results suggest not only an absolute decrease in the population of circulating T lymphocytes in those elderly humans; but very likely, at least in some cases, a functional impairment of T cells.
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Conditions are selected for the killer induction during primary and secondary responses in the one-way MLC, stimulated by x-irradiated or killed allogenic lymphocytes. MIF is found in the MLC culture medium as a sharp peak on the 2nd or the 3rd day of the primary reaction, or as a plato from the 1st day of the secondary reaction. In contrast, the killers are shown to be induced much later reaching their maximum on the 5th and the 4th days, respectively. If heated, instead of irradiated, allogenic lymphocytes were used for stimulation of the primary MLC reaction, the MIF-producer kinetics was not changed, but the killer induction was found to be delayed.
In the indirect assay for leukocyte migration inhibitory factor (LIF), lymphokine-rich supernatants were obtained by culture of stimulated lymphocytes and then tested for LIF activity in agarose plates using purified granulocytes as target cells. Studies on the standardization of the conditions under which LIF acts on the target cells are described, with emphasis on the use of "standard" supernatants of known LIF activity and the influence of pH on the action of LIF and the sensitivity of the assay. The observation that LIF activity is reduced when the ambient pH falls below 7.2 is suggested as an explanation firstly for the "escape" phenomenon seen particularly in capillary tube assays for LIF, and secondly for the reduced sensitivity of the capillarly tube assay in comparison with the corresponding agarose plate assay.
Immune checkpoint inhibitors show insufficient efficacy against pancreatic ductal adenocarcinoma (PDAC). The tumor microenvironment (TME) has a remarkable influence on responsiveness to cancer immunotherapy. The aim of this study was to investigate immunosuppressive characteristics of TME in PDAC tissues. The flow cytometry (FCM) of PDAC surgical specimens revealed that the profile of tumor-infiltrating leukocytes was classified into myeloid cell- and T-cell-dominant subtypes; the myeloid subtype was associated with poorer patient outcomes. Myeloid-derived suppressor cells (MDSCs) showed the highest hazard ratio among various myeloid cell types. Single-cell RNA sequencing and FCM revealed that most MDSCs, but not lymphocytes, in PDAC tissues characteristically express CD74. Macrophage migration inhibitory factor (MIF), a CD74 ligand, was highly expressed in cancer-associated fibroblasts (CAFs) and cancer cells. Spatial transcriptomics demonstrated that the MIF-CD74+ myeloid cell interaction was recognized in CAF-dominant areas in PDAC tissue. CAFs expressing immune suppressor molecules such as MFAP5 and LRRC15 were consistent with MIF+ CAFs. Furthermore, MIF+ CAFs enhanced the migratory activity of MDSCs and promoted MDSC induction and activation. In the murine model, MDSCs were significantly increased in MIF-expressing PDAC tumors, as were CD74+ M-MDSCs per M-MDSC, confirming in vivo interaction between CD74 and MIF. MDSCs play a crucial role in creating an immunosuppressive TME in PDAC; the MIF-CD74 axis drives interactions between MDSCs and CAFs.
Lymphocytes from 80% of patients with infectious mononucleosis in this study failed to produce macrophage migration-inhibition factor in response to partially purified early antigen of Epstein-Barr virus or to tetanus toxoid, whereas lymphocytes from normal subjects did produce this lymphokine. Subsequent analysis of serum from the patients with infectious mononucleosis revealed a serum factor that completely abrogated antigen-specific inhibition of migration by human leukocytes as well as lymphocyte blastogenesis. The serum blocking factor was present in sera from 11 (73%) of 15 patients with infectious mononucleos but only in sera from two (13%) of 15 normal subjects. Samples of serum from five of the patients with infectious mononucleosis and five normal subjects were fractionated with use of Sephadex G-200 gel filtration, and the eluants were assayed for several substances known to inhibit cell-mediated immunity. Serum blocking factor activity could be demonstrated only in fractionated sera from patients with infectious mononucleosis. The serum blocking factor is postulated to be either a soluble immune complex or some as yet unidentified immunoregulatory globulin contained in the IgG fraction of human serum.
This report describes the clinical improvement and acquisition of tuberculin skin-test sensitivity by a tuberculin-negative, drug-resistant patient with lupus vulgaris after a single injection of dialyzable transfer factor (TFd) from a tuberculin-positive healthy donor. The patient's lymphocytes showed a slight response to tuberculin in the leukocyte migration inhibition test and in the lymphocyte transformation test before TFd injection. The acquisition of cellular immunity to tuberculin was demonstrated in vitro by enhanced tuberculin-induced blast transformation. A good correlation between skin test and in vitro tuberculin sensitivity and clinical improvement was seen during the three years that the patient was observed.
The migration inhibition of guinea pig peritoneal macrophages by a factor(s) from media obtained from blue tongue virus-infected monolayer cultures was studied. Medium from blue tongue virus-infected sheep fetal cell cultures inhibited migration of guinea pig macrophages from agarose droplets. Medium from control cultures and stock virus did not inhibit macrophage migration. Medium containing migration inhibiting factor(s) in vitro induced an inflammatory reaction in the skin of a newborn sheep. The inflammatory reaction was observed 20 h after intradermal inoculation. The skin reaction consisted of infiltrates of mononuclear leukocytes in the superficial dermis. Control medium and stock virus caused no skin reaction.
Puromycin treatment of lymphocytes was used to develop a one-way test for leukocyte migration inhibitory factor (LMIF) production in the mixed lymphocyte culture (MLC) reaction. Lymphocytes incubated with this protein synthesis inhibitor induced a vigorous mediator production by nontreated allogeneic cells, being themselves unable to respond to stimulator cells. When puromycin-treated cells were stimulated with the mitogens PHA, ConA, or PWM, overall protein and DNA synthesis were significantly decreased with concomitant abolishment of LMIF production. Viability of stimulator lymphocytes was found to be essential for generation of the mediator in MLC reaction.
By means of the migration inhibition test, the influence of the synovial fluid of rheumatoid arthritis patients on normal blood lymphocytes was investigated. There was the hypothesis that the migration inhibitory factor is already formed in the synovial membrane of rheumatoid arthritis patients. In 35 cases a migration inhibition could be demonstrated, in 3 cases the migration of normal lymphocytes remained uninfluenced, in 6 cases a migration enhancement occurred. The demonstration of the rheumatic factor in the synovial fluids used was partly positive, partly negative. Especially the demonstration of a migration enhancement--this phenomenon could be reproduced repeatedly--cannot yet be interpreted unequivocally and requires further investigations.
An antiserum, (anti-lymphokine globulin, ALyG) directed against highly purified products of activated lymphocytes, inhibits the proliferation of responding cells in guinea pig mixed leukocyte cultures ((MLC). This serum recognizes three newly synthesized lymphocyte products (one of them being migration inhibition factor (MIF) which are involved in the mediation of delayed hypersensitivity reactions in vivo. Since ALyG does not appear to contain cytotoxic antibodies against guinea pig lymphocyte antigens and its inhibitory activity cannot be removed by absorption with lymphoid cells it seems likely that the inhibition of MLC reactivity is not mediated by the lysis of stimulator or responder cells and its target is not the lymphocyte per se but possibly some factor elaborated during MLC response. By contrast, antisera with specificity for histocompatibility (H) antigens can inhibit the MLC when the appropriate H antigens are present on the responding and/or stimulating cell population. However, this inhibitory of the antisera can be effectively absorbed with lymphoid cells bearing the appropriate H antigens. The addition of ALyG even 48 hr after the initiation of culture results in a marked inhibition of MLC reactivity. This finding is consistent with the elaboration of a mitogenic factor or signal during the first 48 hr of culture and the delivery of this signal to the responding cell population. Thus, ALyG does not appear to interfere with the synthesis of this factor but must be present after its release in order to block responder cell proliferation. Furthermore, the stimulatory effect of this MLC mitogenic factor, but not of PPD-induced mitogenic factor on "third party" cells can be completely inhibited when the cells are cultured in the presence of ALyG. These findings suggest that the MLC-mitogenic factor in this system is identical to or cross-reactive with one or both of the newly synthesized molecules recognized by the ALyG.
The presence of 300 microgram gold and cadmium and 10 microgram mercury chloride per millitre of survival medium, during the process of T.I.M.L., results in the release by human lymphocytes of soluble factors which inhibit migration of leucocytes (L.I.F. and M.I.F.). This stimulation of cellular immunity suggests that the anti-infectious therapeutic effect of gold and mercury inorganic salts results from activation of the histiocytary system, through the release of these lymphokins.
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The inhibition factor of the leukocytic migration was studied in 26 patients with Acne Vulgaris, stages III and IV, being positive in all the cases. The LIF positive shows the mobilisation of lymphocytic population, answering an active and constant immunologic conflict. As the PA is antigenic, because it produces a blastification (TTL positive), we can say that it acts as antigen provoking immunologic mechanisms with help to explain the inflammatory process at the pilosebaceous follicle in the AV.