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To determine whether T cells which produce large amounts of latent TGF-beta1 are capable of down-regulating autoimmune and allergic disease, myelin basic protein (MBP)-specific and ovalbumin (OVA)-specific BALB/c cloned Th1 cells were transduced with cDNA for murine TGF-beta1 by coculture with fibroblasts producing a genetically engineered retrovirus. The transduced MBP-specific Th1 cells were found to lose the capacity to provoke EAE in BALB/c mice, and to gain instead the ability to protect against EAE in (SJLxBALB/c) F1 mice immunized with proteolipid protein (PLP). This protective effect was not obtained with OVA-specific TGF-beta1 transduced Th1 cells. The transduced OVA-specific Th1 cells did protect against airway hyperreactivity induced by Th2-cell mediated responses to inhaled OVA. This effect was again antigen specific and it also could not be obtained with untransduced OVA-specific Th1 cells. In both cases these effects of antigen specific TGF-beta1 transduced T cells were nullified by administration of neutralizing anti-TGF-beta mAb. Thus, the antigen specificity of the cloned T cells allows the site-specific local delivery of therapeutic active TGF-beta1 to both Th1 and Th2 cell-mediated inflammatory infiltrates.

A myelin basic protein (MBP)-specific BALB/c T helper 1 (Th1) clone was transduced with cDNA for murine latent transforming growth factor-beta1 (TGF-beta1) by coculture with fibroblasts producing a genetically engineered retrovirus. When SJL x BALB/c F1 mice, immunized 12-15 days earlier with proteolipid protein in complete Freund's adjuvant, were injected with 3 x 10(6) cells from MBP-activated untransduced cloned Th1 cells, the severity of experimental allergic encephalomyelitis (EAE) was slightly increased. In contrast, MBP-activated (but not resting) latent TGF-beta1-transduced T cells significantly delayed and ameliorated EAE development. This protective effect was negated by simultaneously injected anti-TGF-beta1. The transduced cells secreted 2-4 ng/ml of latent TGF-beta1 into their culture medium, whereas control cells secreted barely detectable amounts. mRNA profiles for tumor necrosis factor, lymphotoxin, and interferon-gamma were similar before and after transduction; interleukin-4 and -10 were absent. TGF-beta1-transduced and antigen-activated BALB/c Th1 clones, specific for hemocyanin or ovalbumin, did not ameliorate EAE. Spinal cords from mice, taken 12 days after receiving TGF-beta1-transduced, antigen-activated cells, contained detectable amounts of TGF-beta1 cDNA. We conclude that latent TGF-beta1-transduced, self-reactive T cell clones may be useful in the therapy of autoimmune diseases.

A study was made of the ability of the superantigen staphylococcal enterotoxin B (SEB) to induce relapses of experimental allergic encephalomyelitis (EAE) in SJL mice that had partially or completely recovered from acute EAE. We find that a single injection of 0.05 mg SEB i.v. induces mild relapses in 50% of such mice. In addition, tumor necrosis factor (TNF)-alpha (0.2 micrograms, i.p.) also induces EAE relapses in 43% of SJL mice when injected 1-2 months after recovery. SEB does not induce a second relapse if reinjected when V beta 17a+T cells are still partially deleted. In these mice, however, TNF-alpha is equally effective in inducing relapses as in mice that did not receive SEB previously. We showed earlier that transforming growth factor (TGF)-beta and TNF-alpha have antagonistic effects on experimental autoimmune diseases; e.g., in spontaneously relapsing EAE, TGF-beta and anti-TNF were protective, while anti-TGF-beta caused disease exacerbation. Interleukin (IL)-10 is also known to counteract certain TNF effects. We now find that both human IL-10 and TGF-beta 2 lower the incidence of EAE relapses when given simultaneously with SEB or TNF-alpha. The protective effect of TGF-beta is significant only against relapses induced by SEB (reduced to 9%), and that of IL-10 only against relapses induced by TNF (reduced to 0%) with the treatment regimens employed. Neutralizing anti-TGF-beta does not increase the incidence of SEB-induced EAE relapses. In contrast, anti-IL-10 increases both the incidence and the severity of such relapses. We conclude that TNF production is probably important in causing EAE relapses, but that other aspects of the SEB-induced reactivation of myelin-specific T cells also contribute. Furthermore, endogenous IL-10 rather than TGF-beta production appears to limit the susceptibility to induction of EAE relapses in this model.

Resistance to experimental allergic encephalomyelitis (EAE) induction by homogenized myelin (MSCH) in complete Freund's adjuvant (CFA) and pertussigen (P) in SJL mice was seen 1 week after intravenous injection of PLP 139-151 coupled to spleen cells (PLP-ECDI-SP). Although this resistance could be transferred by spleen cells enriched for CD8+ T cells and thus had a component of immunoregulatory T cells, it was primarily due to anergy, as it was reversible by four daily injections of interleukin (II)-2 starting 3 days after the PLP-ECDI-SP. Earlier treatment with IL-2 did not reverse the tolerance. In view of the known higher sensitivity to anergy induction of Th1 than of Th2 cells, a change in the cytokine balance in the response to MSCH+CFA after anergy induction might be responsible for the resistance to EAE induction. The effect of treatment with cytokines alone on induction of EAE was therefore also determined. Short-term (1-2 weeks) daily pretreatment with IL-2 (4000 U) or TGF-beta 2 (1 micrograms) somewhat decreased the susceptibility to subsequent EAE induction, but IL-4 (5 ng), IL-10 (5 micrograms) or IL-12 (50-200 ng) had no effect under those conditions, even if low doses of PLP were injected simultaneously. Daily injections of IL-4 over an 8-week period prior to immunization, however, significantly lowered the incidence of EAE. Simultaneous injections of IFN-gamma (2000 U/day) completely abolished this effect of IL-4. The effect of these cytokines administered immediately after the immunization with MSCH + CFA + P was also examined. As shown earlier, TGF-beta 2 (100-1000 ng/day) caused a marked protection when it was given intraperitoneally on days 5-9 after injection of MSCH + CFA. IL-4 (5 ng/day), in contrast, was very protective when administered on days 0-4 and less so when given on days 5-9 or even on days 0-12. IL-10 (1 microgram/day) was not protective under these conditions and IL-12 (50 ng/day) significantly increased the severity and mortality of EAE when given on days 0-4 after MSCH + CFA.

Injection of transforming growth factor beta 1 (TGF-beta 1) for five days during the late phase of the immunization process leading either to collagen type II induced arthritis (CIA) or to experimental allergic encephalomyelitis (EAE) protects against the development of these auto-immune diseases. Tumor necrosis factor alpha (TNF-alpha) injected during this same interval aggrevates CIA. In addition, anti-TGF-beta exacerbates and anti-TNF protects against CIA, acute and relapsing EAE, suggesting an important regulatory role for the endogenous production of the two cytokines on the severity of these diseases. More detailed studies about the mechanism of action of TGF-beta in acute EAE show that there is no detectable effect of TGF-beta on the development of sensitized T cells in vivo, as assayed by the proliferative responses of T cells from lymph nodes and peripheral blood to myelin antigens. Nevertheless, the number of lymphoid cells infiltrating the central nervous tissue is much greater in untreated than in TGF-beta-treated, protected mice. We conclude that it is likely that TGF-beta protects against experimental auto-immune diseases by interfering with the entry of lymphoid cells into the target organs through inhibition of the upregulation of adhesion molecule expression on endothelial cells, and with subsequent inflammatory processes inside the target organs by antagonizing both the production and the effects of TNF.

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease in which peripheral lymphoid cells are activated by immunization with myelin proteins and become effector cells that traverse the central nervous system (CNS) capillaries and initiate inflammatory demyelinating lesions. The administration of transforming growth factor-beta (TGF-beta) has been shown previously to decrease the incidence and severity of EAE. In our studies we have determined: 1) the effects of TGF-beta injected at different intervals after the EAE-inducing immunization; 2) the effect of TGF-beta on the development of sensitized T cells, as assayed by the proliferative responses of T cells from lymph nodes and peripheral blood; 3) the extent of lymphoid cell infiltration in CNS of TGF-beta-treated and control mice; and 4) the role of endogenous TGF-beta and TNF in determining the severity of both acute and relapsing EAE. The onset of acute-EAE in SJL mice, induced by immunization with spinal cord homogenate in CFA and pertussigen, is on days 10 to 15. Although daily i.p. injections of 0.2 to 2 micrograms TGF-beta 1 or TGF-beta 2 on days 5 to 9 after immunization are highly protective, injections on days 1 to 5 or 9 to 13 are not. Moreover, anti-TGF-beta accelerates and aggrevates EAE when given on days 5 and 9, but not on day 12. Anti-TNF, injected on days 5 and 9, provides a comparable degree of protection as does TGF-beta. Similarly, in relapsing EAE, anti-TGF-beta increases, whereas anti-TNF decreases the incidence and severity of relapses. TGF-beta treatment on days 5 to 9 does not influence the appearance of sensitized cells in peripheral blood and lymph nodes, but does prevent the accumulation of T cells in brain and spinal cord, as assayed on days 15 to 20. It is concluded that the protective effect of TGF-beta is exerted at the level of the target organ, CNS and/or its vascular endothelium, rather than through a direct effect on lymphoid cells, and that there is a small window of 4 days in which TGF-beta exerts its protective effect.

beta-Trace, a 23.5 kDa glycoprotein of unknown biological functions, is present in all body fluids tested. It is found in higher concentration in human seminal fluid and cerebrospinal fluid (CSF) than in serum. A one-step procedure for the isolation of beta-trace from pooled CSF is described, by affinity chromatography using a specific antibody made against beta-trace. Amino terminal sequence analysis yields the sequence A P E A Q V S V Q P N F Q Q D K F L G with no homology to known proteins, indicating that beta-trace is a novel CSF protein.

Interleukin 1 (IL-1) and tumor necrosis factor alpha are thought to contribute to the inflammatory response associated with autoimmune diseases. Transforming growth factor beta 1 (TGF-beta 1) counteracts many effects of these cytokines and has various immunosuppressive properties. In the present study, it is shown that microgram amounts of TGF-beta 1, injected daily for 1-2 weeks, protect against collagen-induced arthritis (CIA) and relapsing experimental allergic encephalomyelitis (REAE), the animal models for rheumatoid arthritis and multiple sclerosis, respectively. When administered during induction of the disease, TGF-beta 1 prevents CIA but only delays the onset of REAE by 2-3 days. However, when administered during a remission. TGF-beta 1 prevents the occurrence of relapses in REAE. The results suggest that TGF-beta 1 has powerful anti-inflammatory effects, mimicking in some respects the beneficial effects of immunosuppressive drugs in these experimental models of autoimmune disease, but without discernable adverse effects.

The effects of kaolin-induced hydrocephalus on CSF turnover was studied in rats by ventricular perfusion and the results compared to normals. The mean CSF formation rate measured in 20 normal rats was 2.83 microliter/min. Approximately three weeks after intracisternal kaolin, the mean CSF formation rate in 17 hydrocephalic rats was reduced by 40%. CSF absorption in hydrocephalic and normal rats varied linearly with perfusion pressures between -10 and 10 cm H2O. The response of CSF absorption rate to changes in intracranial pressure was decreased in hydrocephalic rats. Ventriculomegaly of hydrocephalic rats was associated with a dilated spinal cord central canal. This suggests that kaolin hydrocephalus alters CSF pathway in rats in a manner similar to that described previously in cats and dogs. Ventriculomegaly is limited by the supporting structures of the brain because the removal of the calvarium and dura after kaolin results in massive ventriculomegaly.

The resistance to cerebrospinal fluid (CSF) absorption through the alternative CSF absorption pathway in kaolin-induced hydrocephalic cats was measured by the constant infusion-manometric test. The cerebral ventricles were bypassed, and artificial CSF was infused directly into the central canal of the spinal cord. The infusion rates were increased stepwise from 0.022 to 0.168 ml/min when the capacity to absorb CSF was exceeded. There was an initial increase in resistance which was associated with the emergence of infusion fluid through a slit-like opening in the dorsal columns of the lower lumbar spinal cord. The resistance to flow decreased when the infusion rate was greater than 0.086 ml/min. Fluid accumulated in the spinal subarachnoid space when the ability to absorb was exceeded. The diversion of this fluid caused the pressure in the spinal cord central canal to fall rapidly. The results suggest that the CSF absorption deficit in chronic kaolin-induced hydrocephalic cats is probably caused by the restriction of CSF flow from the central canal through the spinal cord and into the spinal subarachnoid space. As a result of kaolin, the central canal is sufficiently dilated to permit, during infusion, the flow of at least five times as much CSF as the hydrocephalic cats produce. It is not clear whether the overloading of the CSF absorption mechanism is due to the restrictions imposed by the size of the subarachnoid space, or to the structures in this space involved with the return of CSF to the blood.

This communication describes a reproducible model for the generation of intracranial pressure plateau waves by obstructing the spinal cord central canal of cats with experimentally induced hydrocephalus.

Various injection schedules of C. parvum and tumor cells of the nitrosourea-induced malignant neurinoma, TR-481, were used to induce tumor immunity in syngeneic CDF rats. Although subcutaneous injection of the poorly immunogenic TR-481 cells alone or with C. parvum caused retardation of growth of 2 x 10(5) TR-481 cells injected 1-3 weeks later, no significant difference in tumor size or incidence was obtained, as judged by tumor growth at 8 weeks. In contrast, injection of TR-481 with C. parvum into C. parvum-presensitized rats caused a more significant degree of tumor immunity with complete inhibition of the challenge tumor growth in 17-33% of the animals. Repeated subcutaneous injection of gamma-irradiated TR-481 tumor cells mixed with C. parvum also proved effective, resulting in absence of tumor growth in 40% of the rats. Tumor immunity was specific, since growth of an unrelated tumor was unaffected. It is suggested that local immunological reactivity to C. parvum in the immunizing tumor promotes development of specific tumor immunity.

The exchange of sodium between blood, brain, and cerebrospinal fluid was studied in normal and kaolin-induced hydrocephalic cats. The ventricles were perfused to measure fluid formation and Na+ exchange rates. 22Na was added to the perfusion fluid or injected intravenously as a tracer for Na+ movement. Na+ and 22Na were also measured in cortical gray and white matter. Na+ relative specific activities were calculated for brain, effluent fluid, and serum. With 22Na in the perfusion fluid, Na+ exchange was not different from nascent Na+ influx for both normal and hydrocephalic cats. Na+ relative specific activities of cortical gray and white matter were 10 times greater in hydrocephalic than in normal cats. This difference in Na+ relative specific activity for brain may be due to a higher diffusion constant or to a lower brain capillary permeability. When 22Na was given intravenously, the Na+ diffusional exchange for normal cats was less than that measured when 22Na+ was in the perfusion fluid. In hydrocephalic cats, the Na+ diffusional exchange was effectively zero. Na+ relative specific activities of cortical gray and white matter were the same for normal and hydrocephalic cats. These findings suggest that the impaired Na+ diffusional exchange may be due to pathological changes in the choroid plexus.

Standard techniques for performing carotid angiography in dogs and in man were adapted to the cat in order to study the vascularization of both intracranial and extracranial structures. Venous drainage was examined by venography of selected vessels. The carotid-cerebral and the vertebral-basilar arterial systems of the cat were studied, although no attempt was made to define the territory supplied by each system. In serial angiograms, vascularization of the rete mirabile conjugatum was visualized and distinct arterial and venous retia were delineated. Large facial veins were seen approximately one second after the intra-arterial injection of radio-contrast material. The early filling of the large facial veins appeared to be the result of an artery-to-venous shunt. Contrast material flowed posteriorly in these veins and drained into the venous rete. When contrast material was injected either into the sagittal sinus or retrograde in the external jugular vein, the internal jugular vein was visible in four of ten cats. This vessel drained blood directly from intracranial contents before anastomosis with the vertebral and external jugular veins.

The fall in cerebrospinal fluid (CSF) glucose and CSF leukocyte response was studied in cats with experimental meningitis. Klebsiella pneumoniae or Streptococcus pneumoniae were injected intracisternally, and the latter organisms were incubated with CSF in vitro. When 10(6)-10(9)K. pneumoniae were incubated with 4 ml of CSF, the time time necessary for the glucose to decrease to less than 10 mg/dl ranged from 6.5 to 2.5 h, at a rate proportional to the size of the inoculum. When the same numbers of bacteria were injected intracisternally, the time ranged from 9 to 3 h, and the CSF leukocyte response did not exceed 1200 WBC/mm3. At this time, only minimal histological changes in brain and choroid plexus were seen. Twenty hours after intrathecal K. pneumoniae, large numbers of leukocytes (up to 4 X 10(4)/mm3) were recovered from the CSF. Regardless of the number of leukocytes, however, hypoglycorrhachia occurred when the CSF contained more than 10(7) bacteria/ml. At this interval, large numbers of leukocytes were seen invading the stroma of the choroid plexus, leptomeninges and perivascular spaces. When 10(8) S. pneumoniae were injected intracisternally, CSF glucose concentration decreased as rapidly as with K. pneumoniae. The spinal fluid leukocyte response to S. pneumoniae was, however, greater than that to K. pneumoniae. These results suggest that under the conditions of these studies, hypoglycorrhachia of bacterial meningitis is the result of metabolism of the bacteria with little contribution from the leukocytes.

We studied the changes in ventilation induced by intracisternal administration of enkephalins in four unanesthetized adult dogs. Instantaneous minute ventilation (VT/TT) decreased markedly after D-Ala-Met-enkephalinamide (DAME). Mean VT/TT decreased maximally by 20-50 min after DAME and lasted an additional 15-60 min; by 2 h, VT/TT had returned to base line. Four doses (5, 25, 60, and 125 micrograms/kg) of DAME were used, and the ventilatory response depended on the dose. Mean inspiratory time decreased but mean expiratory time and mean TT showed a marked prolongation. Periodic breathing (2-3 breaths separated by long apneic pauses) occurred in every study and the frequency of sighs increased considerably. All these ventilatory changes were reversed by low doses of naloxone or naltrexone; in addition, VT/TT increased well above base line after the administration of these antagonists. However, naloxone did not increase VT/TT when injected without prior administration of DAME. We conclude that 1) the decrease in VT/TT is due to a decrease in respiratory duty cycle; 2) periodic breathing and increased frequency of sighs constitute part of the changes in the ventilatory pattern induced by DAME; 3) a ventilatory withdrawal reaction may occur after a receptor-agonist interaction of short duration; and 4) although enkephalins can modulate ventilation and the breathing pattern in a major way, these data provide no evidence suggesting that this modulation is tonic.

Effects of changes in serum osmolarity on volume flow of fluid into the cerebral ventricles of cats were measured by ventriculocisternal perfusion with mock cerebrospinal fluid (CSF), mock CSF containing acetazolamide, or a 30 mOsm/liter sucrose solution. Serum osmolarity was altered by intravenous infusion of a sucrose solution ranging between 10 and 650 mOsm/liter changing volume flow. For all perfusion fluids, regression lines relating volume flow to infused solution osmolarity were parallel. After infusion of a 10 mOsm/liter solution, brain water content increased. One hour after infusion, volume flow returned to normal, although serum was still hypotonic. Gray matter water content was still elevated; white matter returned to normal. The results suggest that the source of increased volume flow is the brain, and that the CSF acts as a sink, limiting excess water accumulation during water intoxication.

Cerebrospinal fluid (CSF) turnover and glucose influx were measured in normal and kaolin-induced hydrocephalic rats. The CSF formation rate of normal rats was 2.8 microliter/min and after intracisternal kaolin it was reduced to 1.8 microliter/min. The CSF-serum glucose concentration ratio of normal rats was 0.57 and was reduced to 0.47 in hydrocephalic rats. The reduction was associated with a decrease in the net influx of glucose measured in hydrocephalic rats. The fraction of serum glucose transported from blood to CSF in normal and hydrocephalic rats decreased as serum glucose increased above 200 mg/dl. At all serum glucose concentrations studied, the influx of glucose in normal rats was always 2.6 times greater than that in hydrocephalic rats. These results suggest that because the glucose transport mechanism of both groups of rats is only quantitatively different, the number of sites available for glucose transport from blood to CSF is reduced in hydrocephalic rats.

Adult cats with hydrocephalus were sacrificed at varying times following valveless ventricular shunting. This shunting resulted in a prompt reduction of ventricular size and rapid gross reconstitution of cortical mantle. Ultrastructurally it was evident that white matter edema persisted for many weeks, even in the presence of normal size ventricles. The areas most severely affected by the hydrocephalus such as the corpus callosum showed a paucity of myelinated fibers and their replacement by numerous reactive astrocytes. Reconstitution of the cortical mantle consists predominantly of a diminution of white matter edema and reactive astrocytosis. Clinical improvement undoubtly results from the functional improvement of remaining elements rather than from the replacement of lost elements. This scheme of hydrocephalus suggests that if hydrocephalus is relieved when only ependymal disruption and periventricular water accumulation have occurred, it may be reversible. The subsequent sequence of events consisting of axonal degeneration, myelin disruption and reactive astrocytosis may be less, if at all reversible.

An approach to the treatment of neonatal hydrocephalus is proposed which is intended to reduce or eliminate shunt dependency by increasing the effectiveness of remaining pathways of absorption of cerebrospinal fluid. In suitable cases, intermittent cranial compression by means of an elastic bandage or a helmet with an inflatable inner-lining may be effective. Hydrocephalus was arrested in nine of 14 children treated with this method, eight of whom have developed normally. When cranial compression is contra-indicated or not successful, the preferred method of treatment is an 'on-off' type of valve which is used intermittently to drain a fixed volume of cerebrospinal fluid. Of 18 children who had such shunts inserted, 10 have become totally independent of their shunts and their hydrocephalus has become compensated. All are of normal intelligence. Subtemporal craniectomy was performed on seven shunt-dependent children with recurrent catheter obstruction. Four have been followed for six months and three for two years and in no case has there been further malfunction of the proximal catheter.

CSF volume flow and sodium (Na+)-influx rates in normal and kaolin-induced hydrocephalic cats were measured during ventricular perfusion with anisotonic sucrose solutions. When ventricular fluid osmolality was 120 mOsm, CSF volume flow ceased for both groups of cats. As ventricular fluid osmolality was increased, the CSF volume flow rate of normal cats increased to 70 microliter per minute, and in hydrocephalic cats to 40 microliter per minute. In normal cats, for ventricular fluid osmolality between 50 and 350 mOsm, Na+-influx was constant and thought to occur by diffusion; while for higher osmolalities, Na+-influx increased. In hydrocephalic cats, Na+-influx increased over the entire range of ventricular osmolality but was less than in normal cats. Acetazolamide decreased the CSF volume flow in normal cats by 40 percent, but was ineffective in hydrocephalic cats. These results suggest that CSF secretion by the choroid plexus of cats with kaolin-induced hydrocephalus is impaired.

The turnover of cerebrospinal fluid (CSF) glucose was studied in cats during steady-state perfusion. In all experiments, the perfusion fluid contained either tracer [14C]glucose alone or tracer glucose along with 4.45 mM unlabeled glucose. In some studies, serum glucose was lowered with insulin. The concentration of glucose and [14C]glucose in the effluent fluid was measured, and the distribution of 14C between glucose and lactate was determined by chromatography. From these values, the extraction of glucose and the metabolism of glucose to lactate were calculated. From the decrease in the specific activity of glucose in the perfusion fluid, the influx of glucose from serum was also determined. During steady-state perfusion, 71% of the radioactivity was recovered in the effluent fluid: 50% in the form of glucose, 6% in the form of lactate, and 15% in forms that were not identified. Thus, 50% of the perfusion fluid glucose was cleared, of which 29% was extracted and 21% metabolized. The influx of glucose was proportional to the serum glucose when the latter was about 2.5 mM or 10.0 mM. During perfusion with tracer glucose only, the concentration of glucose in the effluent fluid was 25% that of serum. The transport of glucose from serum was independent of the glucose concentration gradient between serum and perfusion fluid. However, when perfusion fluid glucose concentration was greater than that of serum, transport was inhibited. These studies suggest that in maintaining CSF glucose at a lower concentration than serum glucose, with equal amounts of glucose entering and leaving the CSF, 50% of CSF glucose concentration cleared is replaced by 25% of serum glucose concentration.

The effects of changes in serum osmolarity on the rate and osmolarity of bulk flow of fluid into the cerebral ventricles and on cortical white and grey matter water content were studied in cats. Bulk flow rates and osmolarities were measured during ventriculocisternal perfusion both before and after intravenous infusion of glucose solutions. Infusions of glucose in concentrations greater than 6% decreased fluid bulk flow rate and its osmolarity. Glucose in concentrations less than 6 percent increased fluid bulk flow rate and decreased its osmolarity. Bulk flow rate and serum osmolarity were found to be linearly related with a coefficient of osmotic flow of minus 0.835 mul/min per mOsm/l. At the extremes of induced serum osmolarities, (290 and 360 mOsm/l) bulk flow rate was either increased by 120 percent or completely inhibited. Effluent osmolarity also increased proportionately to serum osmolarity (0.338 mOsm/l per mOsm/l). When compared to controls, cortical grey and white matter water content increased by 1.9 percent and 2.9 percent, respectively, when the infused glucose concentration was 2.5 percent or less, and decreased by 1.8 percent and 2.9 percent when the concentration was 10 percent or more. The results of these experiments suggest that the increased bulk flow comes from the brain, rather then directly from the blood.

Both Fischer 344 and Sprague Dawley rats showed significant numbers of antibody forming cells (PFC) in deep cervical lymph nodes after intraventricular injection of antigens, including trinitrophenylated (TNP)-hemocyanin, TNP-B. abortus and sheep erythrocytes. This indicated that particular as well as soluble antigens drained to these lymph nodes from the spinal fluid. Other lymph nodes examined did not show increased PFC over background, but levels of PFC in the spleen were significantly elevated after intraventricular injection of each of these antigens. Comparison with dose responses in the spleen after intravenous antigen injection suggested that approximately 20% of the intraventricularly injected immunogens drained to the peripheral blood. The relevance of these findings with respect to the brain as an immunologically privileged site is discussed.

The effects of changes in serum osmolality on the volume flow of fluid into the cerebral ventricles and on brain water content was examined in cats with kaolin-induced hydrocephalus. Slopes of the regression lines relating volume flow and serum osmolality for both normal and hydrocephalic cats are the same. The constant difference in flow rates between the two lines, 7 mul per minute, is probably due to impaired choroid plexuow rates between the two lines, 7 mul per minute, is probably due to impaired choroid plexus function of the hydrocephalic cats. The osmotic pressure gradient that causes the flow of fluid is therefore probably between blood and brain. Under these conditions changes in brain water content of hydrocephalic cats were smaller than in normals and can be related to the edema present in this disorder. Despite the inflammatory response to kaolin, the blood-brain barrier remains intact. From the calculated filtration coefficient, it can be inferred that the flow of water from serum through brain and into cerebrospinal fluid is limited by the resistance of fluid flow through the brain.

The effect of intravenously injected tumor immune spleen cells on growth of 3 X 10(5) gliosarcoma T9 cells injected intradermally (ID) or intracerebrally (IC) into sublethally irradiated CDF rats was evaluated. Spleen cells from donor rats with sufficient immunity to reject 5 X 10(5) T9 cells inhibited the growth of T9 cells mixed with spleen cells in a ratio of 1:25 and injected ID, but could not act after intravenous transfer. However, donor rats which had rejected increasing T9 challenge doses up to 1 X 10(7) cells produced immune spleen cells which, upon IV transfer, could inhibit growth of ID T9 challenge but not of EB-679, an unrelated glioma, in recipient rats. Rejection of IC T9 challenge was also obtained after IV transfer, in recipients of such "hyperimmune" spleen cells, but was less (60% maximum) than that noted after ID T9 challenge (100% maximum). The removal of B cells from the transferred spleen cells did not affect the results, suggesting that the specific immunity was mediated by T cells. We conclude that the special immunological circumstances of tumors growing in the brain renders them less accessible to rejection by systemically transferred immune cells, but it is nevertheless possible to effect a significant incidence of rejection of syngeneic tumor growth in the brain by the intravenous transfer of hyperimmune spleen cells.

Wattle responses of 2-to-8-week-old chickens to phytohemagglutinins PHA-P and PHA-M were studied. Dilutions of PHA-M that did not induce wattle swelling after one injection did cause readily detectable swelling when injected a second time 1 week later. These responses were absent in birds subjected to thymectomy and gamma-irradiation at hatching and in birds treated with cyclosporin A during the week of sensitization, indicating that these responses are T-cell-dependent. Chickens bearing transplantable fibrosarcomas failed to show responses. It is suggested that reactivity to a second injection of PHA-M may be used as a measure of immunocompetence at the T-cell level in very young chickens.

Cerebrospinal fluid pathways were studied in both normal and experimental obstructed hydrocephalic cats by positive contrast ventriculography. Either water soluble or insoluble contrast material was injected into the lateral cerebral ventricles, and radiographs were taken of the head and spinal cord. In the normal cat, the contrast material freely flowed throughout the spinal fluid spaces. The contrast material accumulated in the cisterna magna, and from there extended into the cranial and spinal subarachnoid spaces. In the kaolin-induced hydrocephalic cat, the outlets from the fourth ventricle were obstructed, and direct communication between the ventricular system and the subarachnoid spaces no longer existed. In these cats, the contrast material passed directly down the central canal of spinal cord and its movement was followed throughout the entire length of the canal. At the lower lumbar-sacral regions, the material perforated the cord and flowed into the subarachnoid space. At all levels, the central canal was enlarged and local dilatations were seen extending dorsally.

The net transport of glucose from blood to the cerebrospinal fluid compartment of cats was measured by ventriculocisternal perfusion to determine over a large range of serum glucose concentrations the influence of serum glucose levels and their changes on the net transport rate. Changes in serum glucose levels were followed within minutes by corresponding changes in cerebroventricular effluent fluid glucose concentration. At mean values of serum glucose concentration of 6.2 mM and cerebrospinal fluid formation rate of 24.3 microliter/min, the net glucose influx rate was 1.6 mmol/min. The effluent fluid-to-serum glucose concentration ratio was 0.25 and decreased when serum glucose was greater than 11.1 mM. The rate of glucose transport from blood to effluent fluid during ventricular perfusion was saturable, and approached a maximum of 3.5 mumol/min at serum glucose levels above 22 mM. From the cerebrospinal fluid formation and net glucose influx rates the calculated glucose concentration of nascent cerebrospinal fluid was 6.5 mM and higher than the corresponding serum glucose of 5.6 mM. It is concluded that during perfusion over a wide range of serum glucose concentrations, a saturable mediated glucose transport mechanism can be demonstrated. Changes in serum glucose are rapidly reflected in corresponding effluent fluid glucose levels. From effluent fluid-to-serum glucose concentration ratios and calculations of the glucose in newly formed cerebrospinal fluid, the technique, however, overestimates the glucose influx rates at normal serum glucose levels.