Migration Stimulation Factor Research Articles

Tumor-Associated Macrophages as Incessant Builders and Destroyers of the Cancer Stroma

Tumor-Associated Macrophages (TAM) are key components of the reactive stroma of tumors. In most, although not all cancers, their presence is associated with poor patient prognosis. In addition to releasing cytokines and growth factors for tumor and endothelial cells, a distinguished feature of TAM is their high-rate degradation of the extra-cellular matrix. This incessant stroma remodelling favours the release of matrix-bound growth factors and promotes tumor cell motility and invasion. In addition, TAM produce matrix proteins, some of which are typical of the neoplastic tissues. The gene expression profile of TAM isolated from human tumors reveals a matrix-related signature with the up-regulation of genes coding for different matrix proteins, as well as several proteolytic enzymes. Among ECM components are: osteopontin, osteoactivin, collagens and fibronectin, including also a truncated isoform of fibronectin termed migration stimulation factor. In addition to serve as structural proteins, these matrix components have key functions in the regulation of the vessel network, in the inductionof tumor cell motility and degradation of cellular debris. Among proteolytic enzymes are: matrix metalloproteases, cathepsins, lysosomal and ADAM proteases, and the urokinase-type plasminogen activator. The degrading activity of TAM, coupled to the production of bio-active ECM proteins, co-operate to the build-up and maintenance of an inflammatory micro-environment which eventually promotes tumor progression.

Migration stimulation factor (MStF), from murine b cells, constitutively produced by a t-b hybridoma

Hybridomas were established between murine spleen B cells and the thymoma cell line BW5147, to purify the migration stimulation factor (MStF), a molecule likely involved in immunosuppression. The parental B cells were from Lo/PHA mice previously shown to produce high levels of MStF after immunization by appropriate (tolerogenic) doses of ovalbumin. Among the positive clones, B9 was selected, since it produced high levels of MStF constitutively, and no immunoglobulin. This clone was shown to contain the genome of the B-cell fusion partner, since one of its L chain genes had undergone a VK-JK rearrangement. Isolation of MStF by size-exclusion chromatography showed 2 major peaks of activity, one of which eluted in a 20-kDa, almost protein-free fraction. This elution is unlikely to correspond to the true molecular mass, since MStF was found not to be a protein. Indeed, MStF was TCA-soluble, thermoresistant, highly hydrophobic and protease-resistant, but activity was abolished by neuraminidase digestion. The possibility of its being a small molecule transported by a protein carrier was also ruled out. These results suggest that MStF is a complex molecule containing both sialic residues and a lipid moiety. Experiments are planned to further investigate the chemical structure of this unusual B-cell factor.

Manipulation of Macrophage Migration Inhibition/Stimulation Responses by Adjuvants and Interleukins

C57 B1/6 mice were immunized with bovine serum albumin (BSA) and Freund's complete and incomplete adjuvants in various concentrations. Spleen cells from these animals were subsequently stimulated with concanavalin A (Con A), purified protein derivative or BSA, and lymphokine responses were measured in one-stage migration assays. Con A consistently produced macrophage migration inhibition factor (MIF) responses in nonimmunized animals and those immunized with complete adjuvant. This was switched to migration stimulation factor (MStF) responses by prior immunization with incomplete adjuvant. Immunization with complete adjuvant and with BSA alone was followed by MIF responses to antigenic stimulation whereas incomplete adjuvant promoted MStF responses. The MStF responses to both mitogenic and antigenic stimulation were inhibited by the addition of affinity purified interleukin-1 to the spleen cells. Interleukin-1 also inhibited MStF responses and potentiated MIF responses to Con A stimulation by human mononuclear cells whereas interleukin-2 did not influence these responses.

The cellular basis for differential lymphokine responses to mitogen stimulation

Human mononuclear cells from some individuals produce macrophage migration inhibition factor (MIF) when stimulated with Con A while those of others produce migration stimulation factor (MStF). T cells were responsible for these different responses but T 4 cells produced MIF and T 8 cells produced MStF regardless of the global response which was not explained by the individual T 4:T 8 ratios. Admixing the T-cell subpopulations in vitro revealed that MIF responses switched to MStF responses between T 4:T 8 ratios of 75:25 and 50:50 with MStF responders switching at higher ratios than MIF responders. Pulse exposure to supernatants from Con A-stimulated T 4-enriched cells significantly reduced migration indices resulting from stimulation of fresh cells, promoting MIF responses regardless of the responder status of the supernatant donor. In contrast, supernatants from T 8-enriched cells, when obtained from MStF responders, significantly increased migration indices while there was no effect when the supernatants were obtained from MIF responders. These results suggest that soluble factors from T 8 cells are primarily responsible for determining whether an individual mounts a MIF or MStF response to Con A Stimulation.

In vivo production of macrophage migration inhibition and stimulation factors during the inductive phase of the alloimmune response

This paper offers a study of the production of macrophage migration inhibition factor (MIF), and also of the alternative macrophage migration stimulation factor (MSF), in vivo. Mice were injected with mouse spleen cells, irradiated with a dose of 1500 rads. The animals were divided into three groups, two of which were injected for a second time with irradiated mouse spleen cells. Samples of all fractions obtained by electrophoresis of sera of unimmunized mice had no significant effect of macrophage migration, while unfractionated sera of immunized mice obtained after a second injection of alloantigen as a rule stimulated macrophage migration. The results are evidence that T cells may function in vivo during the period before development of the antigen-specific proliferative response of T cells. The technique used to approach the problem, described in this study, can be used for preparative isolation of purified MIF and MSF without contamination by embryonic calf serum proteins which are usually present in culture in vitro.

Antigen-induced inhibition of autoimmune response to rat male accessory glands.

Pretreatment of rats with low doses of purified fraction of rat male accessory glands (containing the autoantigen) markedly reduced the immune response to autoantigen when animals were subsequently challenged with modified rat male accessory glands in complete Freund's adjuvant. The rats pretreated with low doses of antigen prior to immunization showed marked suppression of delayed-type hypersensitivity reaction (P less than 0.001) when compared to control animals (pretreated with rat lung saline extract or 0.15 M NaCl). There was also enhancement of migration of macrophages in test male rats, whereas the migration was inhibited in control male rats (P less than 0.01). The stimulation of migration found in the male rats in which the response was inhibited would suggest the presence of a migration stimulation factor, which is considered a marker of suppressor cell activity. Humoral immunity was also reduced. Pretreatment of rats with low doses of the antigen markedly reduced the immune response, probably because of the induction of suppressor cells.

Lymphokine responses to mitogenic and antigenic stimulation. Predictive value in renal transplantation.

Immune responsiveness of recipients of renal transplants from cadaver donors was monitored by measuring lymphokine responses to specific (donor antigen) and nonspecific (concanavalin A (Con A)) stimuli. Production of migration inhibition factor (MIF) in response to stimulation by Con A before and 3 days after transplantation correlated strongly with graft rejection and production of migration stimulation factor (MSTF) with graft acceptance. This pattern continued at later time intervals but was more variable. An initial vigorous MIF response to donor cell extract was associated with rejection but subsequent responses to donor extract in the 1st month after transplantation were variable and not predictive of the outcome. In some cases, there was clearly a dissociation of lymphokine responses to donor-specific and nonspecific stimuli.

Macrophage migration inhibition factor (MIF): Reducing the variables

While the phenomenon of macrophage migration inhibition is a useful indicator of lymphokine release, it may be caused by other substances, it is subject to considerable variability, and it may be masked by the concomitant presence of substances stimulating migration. We have investigated certain aspects of the lymphokine macrophage interaction in order to circumvent these problems. Cells from the murine macrophage cell line RAW 264-7 migrated with less variability than fresh guinea pig peritoneal macrophages and were more sensitive target cells for human macrophage migration inhibition factor (MIF). Assays were performed with serum-free and endotoxin-free medium and in all cases in the presence and absence of l-fucose. This added specificity to the assay in that biological MIF activity was invariably blocked by l-fucose whereas migration inhibition produced by antigen complexed antibody, endotoxin, and periodate was not affected by l-fucose. It was also possible to demonstrate MIF activity in mixtures of MIF and migration stimulation factor by using l-fucose. We suggest that MIF activity is determined with less variability by using a macrophage cell line as indicator cells and performing the assays in the presence and absence of l-fucose.

Macrophage migration stimulation factor.

Macrophage migration stimulation factor.

A link between helper and suppressor factors and the lymphokines migration inhibition factor and migration stimulation factor

Spleen and thymus cells from Swiss Webster ICR mice were separated into enriched subpopulations using anti-Lyt-1.2 and anti-Lyt-2.2, and tested for lymphokine production in response to Con A stimulation. The Lyt-1.2 subpopulation, helper cells, produces migration inhibition factor (MIF). The Lyt-2.2 subpopulation, suppressor cells, produces migration stimulation factor, (MStF). This is confirmed in the human system with tμ producing MIF and Tγ, MStF. When MIF-rich supernatants are added to lymphocyte suspensions undergoing transformation in response to phytohemagglutinin (PHA), transformation is significantly increased. This effect is blocked by the addition of 0.1 M l-fucose. In contrast MStF suppresses transformation in response to PHA, and also lowers background counts. It is suggested that MIF is a helper factor, and MStF, a suppressor factor.

Production of factors regulating macrophage mobility in the early period of mixed lymphocyte culture

The macrophage migration stimulation factor (MSF) is produced during the first hours of mixed lymphocyte culture (MLC) in the H-2 system. The activity of MSF is characterized by sharp peaks of migration stimulation in the culture fluids of allogeneic MLC. The peaks appeared every 5 hours. After 12--16 hours in the culture fluids of allogeneic MLC, there has been demonstrated macrophage migration inhibition factor whose activity rose by 48 hours. Optimal concentrations were revealed for stimulation and inhibition of macrophage migrations on the dilution of 1--2-day MLC culture fluids. The existence of the biorhythmical mechanism that controls the macrophage mobility through the balance of soluble mediators with alternative activity is suggested.

Macrophage migration stimulation factor, migration inhibition factor and the role of suppressor cells in their production

Guinea pig lymph node lymphocytes and human peripheral blood lymphocytes when stimulated by specific antigen or mitogen will release factors that affect in vitro macrophage migration. Migration inhibition factor production appears to be under the control of suppressor cells which are T lymphocytes. When suppressor cells are generated by stimulation with Con A for 4 days, migration stimulation factor (M.St.F.) activity is found. In other situations where M.St.F. is found this is thought to be due to increased suppressor cell activity. For example, young adults produce this lymphokine when stimulated with Con A, whereas aged individuals produce MIF. Concanavalin A appears to be the mitogen of choice for M.St.F. production, and phytohemagglutinin for MIF production. The release of this putative factor M.St.F. from suppressor T cells helps to explain some of the difficulties that have existed in studies of macrophage migration inhibition.

Assay of human lymphokines in vitro. Evidence for a migration stimulation factor (MStF) which interferes with the macrophage migration inhibition assay.

When cultured in vitro, human lymphocytes produced a range of materials which were able to reduce the migration inhibitory effect of human macrophage migration inhibition factor (MIF) and in some cases stimulated macrophage migration to greater than control levels. In addition, lymphocytes stimulated with antigen or mitogen produced a lymphokine-like migration stimulation "factor". Detectable production of this factor occurred 24--48 h after antigen stimulation. The migration stimulation factor (MStF) (MW 50-250,000; pI 6-5) was not chemotactic and could be separated from migration inhibition and chemotactic factors by chromatography and iso-electric focussing.

Migration Inhibition Factor (MIF) and Migration Stimulation Factor (MSF) in Fetal Calf Serum

Abstract Non-heat-inactivated fetal calf serum contains a factor, FCS-MIF, that inhibits in vitro the migration of guinea pig peritoneal macrophages. FCS-MIF is partially or completely inactivated by dialysis, repeated freezing and thawing, heating to 56°C for 30 min, and changes of pH beyond the range of 6.0 to 7.7. Chromatography in different gels and with different buffers suggests that several fractions may have MIF activity. FCS also contains a factor, FCS-MSF, that stimulates the migration of guinea pig macrophages. It is detected after MIF is removed by chromatography on DEAE-Sephadex A-25. A stimulatory factor is also present in supernatants of sensitized guinea pig lymphoid cells stimulated with antigen and is detected when the supernatants are treated in the same fashion as FCS to uncover FCS-MSF.