Cooperation between nerve growth factor and laminin or fibronectin in promoting sensory neuron survival and neurite outgrowth.

Chick embryo dorsal root ganglion (DRG) neurons were purified by differential adhesion to plastic. The purified neurons were used to study the cooperation between nerve growth factor (NGF) and laminin or fibronectin in promoting neuron survival and neurite outgrowth. NGF alone supported the survival of only 20% embryonic day 10 (E10) cells, of which only 40-50% had neurites. Treatment of the substrate with fibronectin or laminin increased survival in the presence of NGF up to 80% of the seeded neurons, all of which showed extensive neurite outgrowth. Survival and neurite outgrowth were also enhanced by the combined effects of elevated potassium and laminin. In contrast to E8-10 cells, 85% of E16 neurons survived in the basal culture conditions, i.e. without additional NGF, fibronectin or laminin, although neurite outgrowth was enhanced by all 3 proteins. Antisera to NGF, laminin and fibronectin, each independently decreased survival and neurite outgrowth of DRG neurons, totally with E9 and partially with E16 cells. The results suggest that the cooperative actions of extracellular matrix proteins and NGF are essential for survival and neurite outgrowth of embryonic DRG neurons and that these neuronal requirements change during development.

Prolongation of rat kidney allografts by pretransplant administration of donor antigen extract or whole blood transfusion combined with a short course of cyclosporine.

The immunosuppressive effect of the combination of a three day course of cyclosporine with one i.v. injection of 3M KCL-extracted donor antigen or donor blood transfusion was tested across the strong histocompatibility barrier causing rejection within 8 days of kidney transplants from Buffalo (Buf, RT1b) to Wistar-Furth (WFu, RT1u) inbred rats. Administration of 10 mg/kg/day cyclosporine alone for three days (-1, 0, and 1) slightly prolonged graft survival time from 7 to 11 days. The combination of cyclosporine with donor Buf 3M KCl antigen or with a Buf blood transfurion administered one day prior to transplantation caused greater prolongation of graft survival--19 and 25 days, respectively. Neither third-party BN soluble antigen nor BN blood transfustions acted synergistically with cyclosporine to prolong Buf graft survival. Increasing doses of donor-soluble antigen up to an optimal dose of 5 mg proportionately prolonged graft survival; however, administration of 10 mg antigen was less effective than 5 mg. On the other hand, administration of 1 ml of donor blood achieved the maximal effect. Lymphocytes harvested ten days after transplantation from recipients that had received combined therapy with cyclosporine and donor 3M KCl antigen not only displayed specific unresponsiveness to donor stimulator cells in mixed lymphocyte culture, but also specifically suppressed the proliferative response of syngeneic, virgin WFu responder cells to allogeneic donor Buf but not to third-party BN cells. Furthermore, suppressor cell activity was suggested by diminished responses in an in vivo local adoptive mixed lymphocyte culture assay and by prolongation of Buf kidney survival following systemic adoptive transfer. These findings suggest that immunosuppression with cyclosporine permits induction of specific suppressor cells by 3M KCl donor antigen, resulting in specific unresponsiveness to allografts.

Electrophoretic mobility test (EMT): studies on lymphocyte response and mechanism of the test using a rat tumor model.

After incubation with an encephalitogenic factor from human (HEF) or rat (REF) brain, lymphocytes of Fischer 344 rats bearing a spontaneous mammary adenocarcinoma produced a soluble substance which reduced the mobility of tanned sheep red blood cells in the electrophoretic mobility test (EMT). For studying the kinetics of this lymphocyte response, 6 X 10(5) tumor cells were injected into the hind footpad. In correlation with time and tumor size, one was able to influence the appearance of metastases by amputation of the leg. As early as 16 hours after inoculation of tumor cells, sensitivity of lymphocytes against HEF and a KCl-extract of the tumor could be shown in the EMT. It decreased on days 2 and 5, but was still seen until the day of amputation. Rats without metastases showed sensitivity up to four weeks after amputation and then returned to normal levels. Rats with metastases showed sensitivity until death at about seven weeks later. With the use of Amicon membranes, Sephadex G-50, and ion-exchange chromatography, a protein could be isolated from human basic myelin extract with a molecular weight of about 16,000-20,000 daltons. It had no direct influence on the EIC by itself, but after incubation with lymphocytes from tumor-bearing rats it evoked the production of a slowing substance. Using Sephadex G-100, the slowing substance appeared in the region in front of BSA indicating a molecular weight of greater than 80,000 daltons. It was heat-stable for 30 min at 56 degrees C and was sensitive to trypsin.