Changes in plasma IL-1beta, TNF-alpha and IL-6 after total hip replacement surgery in general or regional anaesthesia

Different anaesthetic methods influence the neuro-immuno-endocrine biologic responses to surgery and may thus possibly interfere with the postoperative course and development of complications. The neuroendocrine system is closely related to the cytokine network. In this study, the effects of general anaesthesia (n=6) and regional spinal/epidural anaesthesia (n=6) on the cytokine response (IL-1beta, TNFalpha, IL-6) to uncemented total hip replacement surgery were evaluated. The postoperative clinical course was uneventful in every case. In both groups, only very low values of plasma IL-beta were measured perioperatively, whereas plasma IL-6 increased postoperatively with peak values 4 h after surgery. The changes in plasma TNF-alpha were not significant. No significant differences in plasma TNF-alpha or IL-6 were found between patients operated in general or in regional anaesthesia. This suggests minor influence of plasma cytokines on the possible beneficial effects of regional anaesthesia on the clinical course after surgery in low risk patients. There were slightly higher TNF-alpha and IL-6 levels after the operation and significantly lower cortisol levels during the operation in the regional anaesthesia group compared to the general anaesthesia group, giving rise to a significant inverse correlation between peak values of IL-6 and peak values of cortisol. This supports the theory that after surgery the inhibitory effect of cortisol on monocyte cytokine production overrides adrenergic stimulation.     

Consequences of concurrent Ascaridia galli and Escherichia coli infections in chickens

   

The principal aim of this study was to evaluate dissociative anaesthesia for castration of colts during field conditions. Three dissociative anaesthetic protocols were evaluated during castration of colts in an animal hospital. The protocol considered to be the most suitable was thereafter evaluated during castration of colts under field conditions. Respiratory and haemodynamic parameters and the response to surgery were determined during anaesthesia. All horses breathed air spontaneously during anaesthesia. Under hospital conditions 26 colts were randomised to receive one of three anaesthetic protocols: Romifidine and tiletamine-zolazepam (RZ); acepromazine, romifidine and tiletamine-zolazepam (ARZ); or acepromazine, romifidine, butorphanol and tiletamine-zolazepam (ARBZ). The surgeon was blinded to the anaesthetic protocol used and decided whether supplemental anaesthesia was needed to complete surgery. Under field conditions 31 colts were castrated during anaesthesia with the ARBZ protocol. All inductions, anaesthesia and recoveries were calm and without excitation under both hospital and field conditions. Surgery was performed within 5–20 minutes after the horses had assumed lateral recumbency during both hospital and field castrations. Under hospital conditions some horses needed supplemental anaesthesia with all three anaesthetic protocols to complete surgery. Interestingly, none of the horses castrated with protocol ARBZ under field conditions needed additional anaesthesia. Cardiorespiratory changes were within acceptable limits in these clinically healthy colts.     

Similar effects of general and spinal anaesthesia on perioperative stress response in patients undergoing haemorrhoidectomy

Surgery induces release of neuroendocrine hormones (cortisol), cytokines (interleukin-6: IL-6, tumour necrosis factor-alpha: TNF-alpha), acute phase proteins (C-reactive protein: CRP, leptin). We studied the effects of general and spinal anaesthesia on stress response to haemorrhoidectomy. Patients were assigned to general and spinal anaesthesia groups (n = 7). Blood samples were drawn before induction and 24 hours after surgery. Perioperative levels of IL-6, TNF-alpha, CRP, cortisol, and leptin were comparable among the groups. Twenty four hours after surgery, TNF-alpha and cortisol did not change; IL-6 and CRP increased significantly in all patients. Significant increase in leptin levels was found in patients undergoing spinal anaesthesia. Except for the increase in leptin levels, there was no significant difference related to the effects of general and spinal anaesthesia.     

The successful use of fentanyl/fluanisone ('Hypnorm') as an anaesthetic for intracranial surgery in neonatal rats

This study reports on the successful use of fentanyl citrate and fluanisone ('Hypnorm') anaesthesia for intracranial surgery in neonatal (7-day-old) rats. Provided the anaesthetic was administered subcutaneously, the animals showed a very high survival rate in the short term (81/85, 95%) and showed no ill effects in the long term. The depth of anaesthesia was sufficient to allow the operation to be carried out without the animal reacting to any painful stimuli. However, the animals did make random movements during the period of surgical anaesthesia which were not related to any painful stimuli. Although these movements did not interfere with the surgery performed here, such movements would interfere with operations requiring greater precision, such as the localized micro-injection of neural tracers.     

Effects of surgery and epidural or general anaesthesia on testosterone, 17-hydroxyprogesterone and cortisol plasma levels in prepubertal boys

Testosterone (T), 17-hydroxyprogesterone (17P) and cortisol (F) plasma levels have been measured in two groups of prepubertal boys before and during surgery under general anaesthesia (Group 1) and epidural anaesthesia (Group 2) respectively. The mean plasma levels of T, 17P and F increased significantly (P less than 0.05; P less than 0.001; P less than 0.005, respectively) during surgery in Group 1; in Group 2 the plasma levels of T and F did not show any significant variation, whereas 17P significantly increased (P less than 0.05). However the mean level reached by 17P in Group 2 was significantly lower (P less than 0.005) than that observed in Group 1. No significant variation of LH and FSH plasma levels was observed in either group. Our report suggests that the modifications of T and 17P plasma levels observed during surgery under general anaesthesia (GA) are probably due to the stress induced adrenal response. This response can be inhibited or reduced by epidural anaesthesia (EA).     

The influence of immunoglobulin on the development of Pseudomonas aeruginosa infection in an immunocompromised mouse model

Pretreatment with normal immunoglobulin G (normal IgG) isolated from human placental blood, in secondary immune deficiency after anaesthesia, surgery and corticosteroid therapy seems to be an effective protection against bacterial infection in clinical practice. For this purpose, we tried to verify the effectiveness of normal IgG in prevention of bacterial infection in an animal model. The influence of treatment with normal human IgG has been studied in mice exposed to a sublethal infection with Pseudomonas aeruginosa in various states of immunocompetence such as under anaesthesia and corticosteroid therapy. Results, evaluated as percentages of survivors, confirm significant protection against infection with P. aeruginosa despite immunodepression with hydrocortisone and anaesthesia (96.6% of survivors in the group treated with IgG as opposed to 30% for the untreated corresponding group--P less than 0.001).     

Cutaneous and subcutaneous blood flow during general anaesthesia

The vasodilator effect of anaesthetic agents on cutaneous vessels has often been investigated. In contrast, although subcutaneous tissue is concerned with metabolism and thermoregulation, the effects of anaesthesia on subcutaneous blood flow have not been well documented. The purpose of this study was to determine the magnitude of changes in cutaneous and subcutaneous blood flow during general anaesthesia in Man. Anaesthesia was induced with flunitrazepam in 15 patients before facial plastic surgery. Blood flow was estimated using heat thermal clearance (HC). Two HC sensors in different areas allowed the measurement of superficial and deep HC. Systolic (SABP), diastolic (DABP) and mean arterial blood pressure (MABP), heart rate (HR), and rectal and mean skin temperature were also recorded. After induction of anaesthesia, HR increased significantly (p less than 0.05) whereas SABP, DABP and MABP remained unchanged. The rectal-toe temperature gradient fell from 6.3 +/- 4.1 degrees C to 3.4 +/- 1.1 degrees C (p less than 0.01) suggesting a reduction in vasomotor tone. Superficial HC increased from 0.37 +/- 0.06 to 0.42 +/- 0.08 W.m-1.degrees C-1 (p less than 0.05) whereas deep HC decreased from 0.33 +/- 0.07 to 0.31 +/- 0.09 W.m-1.degrees C-1 (NS) and returned to the control value thereafter. Rectal temperature and mean skin temperature were unchanged. The changes in deep HC are similar to those previously observed in muscle during induction of anaesthesia. Our results show that anaesthesia mainly affects cutaneous blood flow, without any significant change in subcutaneous blood flow during the early phase of anaesthesia in human beings.     

Effects of anaesthesia on blood gases, acid-base status and ions in the toad Bufo marinus

It is common practice to chronically implant catheters for subsequent blood sampling from conscious and undisturbed animals. This method reduces stress associated with blood sampling, but anaesthesia per se can also be a source of stress in animals. Therefore, it is imperative to evaluate the time required for physiological parameters (e.g. blood gases, acid-base status, plasma ions, heart rate and blood pressure) to stabilise following surgery. Here, we report physiological parameters during and after anaesthesia in the toad Bufo marinus. For anaesthesia, toads were immersed in benzocaine (1 g l(-1)) for 15 min or until the corneal reflex disappeared, and the femoral artery was cannulated. A 1-ml blood sample was taken immediately after surgery and subsequently after 2, 5, 24 and 48 h. Breathing ceased during anaesthesia, which resulted in arterial Po(2) values below 30 mmHg, and respiratory acidosis developed, with arterial Pco(2) levels reaching 19.5+/-2 mmHg and pH 7.64+/-0.04. The animals resumed pulmonary ventilation shortly after the operation, and oxygen levels increased to a constant level within 2 h. Acid--base status, however, did not stabilise until 24 h after anaesthesia. Haematocrit doubled immediately after cannulation (26+/-1%), but reached a constant level of 13% within 24 h. Blood pressure and heart rate were elevated for the first 5 h, but decreased after 24 h to a constant level of approximately 30 cm H2O and 35 beats min(-1), respectively. There were no changes following anaesthesia in mean cellular haemoglobin concentration, [K+], [Cl-], [Na+], [lactate] or osmolarity. Toads fully recovered from anaesthesia after 24 h.     

Effects of anaesthesia and surgery on levels of adrenaline and noradrenaline in blood plasma of the eel (Anguilla anguilla L.)

1. The effects of surgery and anaesthesia on adrenaline and noradrenaline plasma levels were investigated in the eel (Anguilla anguilla L.). 2. Effect of surgery: highest values were obtained when putting back the fish in water. Three hours after surgery, adrenaline and noradrenaline plasma levels were always significantly higher than those obtained 24 and 48 hr after surgery. 3. Effect of anaesthesia: anaesthesia only had no effect on adrenaline and noradrenaline plasma levels. 4. It was concluded that the trauma of surgery was mainly responsible for the elevation of CA plasma levels in the eel. A minimum post-operative period of 24 hr should be allowed before any blood sampling for estimation of resting CA plasma levels. Resting adrenaline and noradrenaline plasma levels, 48 hr after surgery, were respectively 1.31 +/- 0.38 and 3.37 +/- 0.41 pmol/ml.     

Anaesthesia and the acute phase protein response in children undergoing circumcision

Concentrations of acute phase proteins (CRP: C-reactive protein, albumin) change during surgery. We investigated the acute phase response to circumcision and the effects of anaesthesia on this response. The children were divided into four groups; group 1 (intratracheal general anaesthesia, n=40), group 2 (general anaesthesia with mask, n=20), group 3 (ketamine, n=20), group 4 (local anaesthesia, n=35). Blood samples were obtained, 24 hours before circumcision, after premedication, and 24 hours after circumcision. CRP and albumin before circumcision were comparable for all groups. There was no increase in CRP, and albumin remained steady throughout the study. No difference was observed among the groups, and related to anaesthesia. No responsiveness may be explained with the size of injured tissue or anatomical and histological type of preputium.     

Does preoperative administration of metamizol (Novalgin) affect postoperative body weight and duration of recovery from ketamine-xylazine anaesthesia in mice undergoing embryo transfer: a preliminary report

Thirty-two female mice used for embryo transfer or as controls received either metamizol or equal volumes of normal saline administered subcutaneously following induction of anaesthesia with ketamine-xylazine. Body weight was measured immediately before surgery, after 24 and after 48 h. The duration of the surgical anaesthesia was recorded and postoperative behavioural responses were measured. Comparison of the treatment groups revealed no significant differences in body weight and recovery times, nor were other signs of discomfort detected in either treatment group. It was concluded that administration of metamizol did not provide additional analgesia following embryo transfer in mice anaesthetized with ketamine-xylazine.     

Integrity of gut mucosa during anaesthesia in major abdominal surgery

The aim of the study was to examine a perfusion and integrity of small bowel in 60 subsequent patients during the major open abdominal surgery which lasted from 2 to 7 hours. Two samples of the intestinal mucosa were removed: at the beginning, and at the end of the surgical procedure in general anaesthesia. A mucosal injury was classified into 4 grades. pH, PCO2 and lactate level were measured in the blood samples from the arterial and mesenteric vein in one hour time intervals. The changes of intestinal mucosa were found in 31 patients (51.7%): in 19 patients (31.7%) grade 1 changes were recorded, in 10 patients (16.7%) grade 2, and in 2 patients (3.3%) grade 3. Grade 4 lesions were not recorded. There was a statistically significant correlation between grades of the mucosal damage and the surgery duration (p = 0.001). Analysis during the one hour intervals showed that there was no exact time point when the significant aggravation of the pathohistological changes in intestinal mucosa occurred. However, when patients were allocated into two subgroups with surgical procedures lasting less than 4 hours and more than 4 hours, there was a statistically significant difference in the grades of mucosal damage between subgroups (p < 0.05). More biopsies without pathohistological changes were observed in the patients whose procedure duration was < 4 hours. A significantly higher lactate concentrations in arterial and mesenteric venous blood were observed in the patients with pathohistological changes at 6 hours time point as compared to 2 hour time point in the patients without pathohistological changes (p < 0.05). During the open abdominal surgery in general anaesthesia, the length of the procedure influences the grade of the intestinal mucosa injury. Deterioration of the pathohistological findings in the intestinal mucosa correlates with high lactate blood level, suggesting that the cause of these changes may result from tissue hypoxia.     

Cardiovascular changes and catecholamine release following anaesthesia in Chinook salmon (Oncorhynchus tshawytscha) and snapper (Pagrus auratus)

We investigated recovery from anaesthesia in Chinook salmon (Oncorhynchus tshawytscha) with and without surgery. Fish either underwent light sedation on exposure to 60 ppm AQUI-S or surgical depth anaesthesia with 120 ppm AQUI-S. Surgical depth anaesthesia experiments were replicated using New Zealand snapper (Pagrus auratus). During light sedation, there was no evidence of catecholamine release in salmon despite changes in heart rate and blood pressure. Following surgical anaesthesia both salmon and snapper released high concentrations of catecholamines into the circulation. Plasma half-life of adrenaline in salmon was 9.3+/-0.7 min (n = 7) and in snapper was 4.4+/-3.3 min (n = 7). There was no further release of catecholamines, despite attempts by both species to escape their enclosures. Though clearance of the catecholamines was rapid, the cardiovascular effects of anaesthesia were prolonged. Dorsal aortic blood pressure (P(DA)) and heart rate (HR) were high following anaesthesia, falling by 60 min in the 60 ppm exposed salmon but remaining high in the 120 ppm group. Following anaesthesia ventral aorta blood pressure (P(VA)) in snapper was positively correlated with HR, as was P(DA) and haematocrit in salmon. Recovery of cardiovascular control processes is prolonged in recovery from anaesthesia if the fish become hypoxic.     

Should laboratory mice be anaesthetized for tail biopsy?

Tail biopsies are routinely taken to genotype genetically modified mice. However, the effect of this procedure on the wellbeing of the animals has rarely been investigated. Thus, it has not yet been clearly demonstrated to what extent the mice suffer from tail biopsy (TB) and for how long. The aim of our study was to assess the impact of a single TB on the physiological and behavioural parameters of adult mice and to investigate whether or not anaesthesia can be beneficial. Body weight (BW) curves, daily food/water consumption and telemetric measurements of heart rate, body core temperature, and locomotor activity were recorded for three days following TB, both with and without anaesthesia with methoxyflurane (MOF) or diethylether (ether). Additionally, the impact of anaesthesia alone was characterized. TB without anaesthesia induced an increase in heart rate and locomotor activity for 1 h. Body core temperature was elevated for 2 h. In contrast, heart rate was increased for up to 4 h after anaesthesia. Body core temperature remained altered for up to 20 h after exposure to ether and for 44 h after exposure to MOF. BW was slightly reduced after MOF. Cases of death occurred exclusively under ether at a rate of 7%. Our results indicate a short-lived impact of a TB, whereas anaesthesia with either MOF or ether induced remarkable alterations in the parameters analysed. In conclusion, these types of anaesthesia did not improve mouse wellbeing following tail biopsy.     

Studies on the hormonal regulation of fuel metabolism in the human newborn infant undergoing anaesthesia and surgery

Little is known of the endocrine and metabolic milieu in preterm and term neonates exposed to surgical stress. In order to define the effects of anaesthesia and surgery on the hormonal regulation of intermediary metabolism, the levels of plasma insulin, glucagon, adrenaline and noradrenaline were measured in addition to blood glucose, lactate, pyruvate, alanine, acetoacetate, hydroxybutyrate, glycerol and plasma-free fatty acids in 38 neonates (23 term, 15 preterm) undergoing surgery. Blood samples were drawn pre-operatively, at the end of surgery, and at 6, 12 and 24 h post-operatively. Plasma levels of adrenaline and noradrenaline increased significantly in response to surgery. In term neonates, plasma insulin concentrations were unaltered at the end of surgery, but were significantly increased throughout the post-operative period; plasma glucagon levels were unchanged at the end of surgery but had significantly decreased by 24 h after surgery. Insulin levels in preterm neonates remained unchanged during surgery as well as in the post-operative period. All neonates developed a significant peri-operative hyperglycaemia which persisted up to 12 h after surgery. Blood lactate and pyruvate increased during surgery, accompanied by significant increases in plasma free fatty acids, total ketone bodies and glycerol concentrations by the end of surgery. Blood glucose concentrations were significantly correlated with plasma adrenaline levels at the end of surgery and with plasma glucagon at 6 h post-operatively. The insulin/glucose ratio was significantly decreased at the end of surgery in term and preterm neonates. Further analysis showed that total parenteral nutrition given just before surgery and thiopentone anaesthesia given during surgery significantly augmented the peri-operative hyperglycaemic response of term neonates. Thus, stress-related hormonal changes in preterm and term neonates may precipitate a catabolic state characterized by glycogenolysis, gluconeogenesis, lipolysis and mobilization of gluconeogenic substrates in the post-operative period. Prevention of these metabolic derangements by anaesthetic or hormonal manipulation may possibly help to improve the clinical outcome of neonates undergoing surgery.     

Different modulation of the perioperative stress hormone response under neurolept-anaesthesia or enflurane for cholecystectomy.

Two groups of 13 patients, randomly allocated to receive either enflurane or neurolept anaesthesia for cholecystectomy, were compared in their cardiovascular and neuroendocrine response to surgery and in the postoperative period. There were no significant differences in blood pressure or heart rate. Catecholamine values were higher under neurolept anaesthesia towards the end of surgery and postoperatively. Median values for adrenaline during suture of peritoneum were 342 pg/ml and 88 pg/ml, respectively, P less than 0.05. In contrast, ACTH and cortisol rose to higher levels in enflurane treated patients. At the end of surgery median ACTH values were 75 pg/ml in NLA patients and 322 pg/ml in enflurane patients (P less than 0.01). Vasopressin increments during surgery were similar under both regimens, while prolactin was higher following induction of neurolept anaesthesia. It is discussed whether the differences in stress hormone secretion patterns under either form of anaesthesia reflect different stress protective properties or direct pharmacological effects of certain anaesthetics. We conclude that the hormonal stress response to surgery is critically dependent on the type of anaesthesia and may be discordant in different hormonal systems.     

Neutrophil Chemotaxis in Cord Blood of Term and Preterm Neonates Is Reduced in Preterm Neonates and Influenced by the Mode of Delivery and Anaesthesia

Bacterial infections, even without any perinatal risk factors, are common in newborns, especially in preterm neonates. The aim of this study was to evaluate possible impairment of neutrophil chemotaxis in term and preterm neonates compared with adults as well as neonates with different modes of delivery and anaesthesia. We analysed the expression of the adhesion molecule L-Selectin as well as shape change, spontaneous and N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced transmigration of neutrophils in a flow cytometric assay of chemotaxis after spontaneous delivery with Cesarian Section (CS) under spinal anaesthesia (mepivacaine, sufentanil), epidural anaesthesia (ropivacaine or bupivacaine, sufentanil) or general anaesthesia (ketamine, thiopental, succinylcholine). Chemokinesis was higher (p=0.008) in cord blood neutrophils than in the adult ones, whereas those could be more stimulated by fMLP (p=0.02). After vaginal delivery neutrophils showed a higher spontaneous and fMLP-stimulated chemotactic response compared to neonates after CS without labor. Comparing different types of anaesthesia for CS, spinal anaesthesia resulted in less impairment on chemotaxis than general anaesthesia or epidural anaesthesia. The new flow cytometric assay of neutrophil chemotaxis is an appropriate and objective method to analyse functional differences even in very small volumes of blood, essential in neonatology. Term neonates do not show reduced chemotaxis compared to adults. Preterm neonates present with reduced chemotaxis and chemokinesis, confirming the well known deficits in their neutrophil function. The side effects of maternal drugs on the neonatal immune system have to be considered especially when the immune response is already impaired, as in preterm infants.     

Preoperative Acute Normovolaemic Hemodilution (ANH) in combination with Hypotensive Epidural Anaesthesia (HEA) during knee arthroplasty surgery. No effect on transfusion rate. A randomized controlled trial [ISRCTN87597684]

BACKGROUND: Hypotensive epidural anaesthesia (HEA) combines a high epidural anaesthesia, performing a sympathetic blockade, with low-dose iv-infusion of epinephrine to stabilize circulation in the conscious patient. Mean artery blood pressure is reduced to 45-50 mmHg and hereby a reduced blood loss. In this study we have combined HEA with preoperative acute normovolaemic hemodilution (ANH) in attempt to further reduce the blood loss and need for blood transfusion in total knee arthroplasty surgery (TKR). METHODS: Twenty-eight patients scheduled for TKR are randomised to ANH or no hemodilution (non-ANH). Both groups are anaesthetized with HEA. ANH is established with predonation of 20 % of the total blood volume, and replacement with equal volume of HAES 6 %. Blood re-transfusion is completed within 6 h. RESULTS: A mean of 877 ml blood was predonated (19.7 % of the total blood volume). Blood loss was, except from the intraoperative loss, significantly higher in ANH group. The total loss was 1306 mL (ANH) vs. 1026 mL (non-ANH), p < 0.05. Except from the first hour postoperatively, hematocrit was identical in between groups postoperatively. The amount of blood transfusion was identical 386 ml (ANH) vs. 343 ml (non-ANH) (ns). 50 % went through surgery without receiving blood (ANH) vs. 58 % (non-ANH). No renal, neurological or cardiopulmonary complications were registered. CONCLUSIONS: These data suggest no benefits in combining HEA and ANH in TKR surgery. Probably because of the reduced viscosity of the blood after ANH, there is an increased postoperative blood loss. The need for homologous blood transfusion was identical.     

Surgical debulking of podoconiosis nodules and its impact on quality of life in Ethiopia

BackgroundIn Ethiopia, severe lymphedema and acute dermato-lymphangio-adenitis (ADLA) of the legs as a consequence of podoconiosis affects approximately 1.5 million people. In some this condition may lead to woody-hard fibrotic nodules, which are resistant to conventional treatment. We present a series of patients who underwent surgical nodulectomy in a resource-limited setting and their outcome.MethodsIn two teaching hospitals, we offered surgical nodulectomies under local anaesthesia to patients with persisting significant fibrotic nodules due to podoconiosis. Excisions after nodulectomy were left to heal by secondary intention with compression bandaging. As outcome, we recorded time to re-epithelialization after surgery, change in number of ADLA episodes, change in quality of life measured with the Dermatology Quality of Live Index (DQLI) questionnaire, and recurrence rate one year after surgery.Results37nodulectomy operations were performed on 21 patients. All wounds re-reepithelialised within 21 days (range 17–42). 4 patients developed clinically relevant wound infections. The DLQI values were significantly better six months after surgery than before surgery (P<0.0001). Also the number of ADLA episodes per three months was significantly lower six months after surgery than before surgery (P<0.0001).ConclusionNodulectomy in podoconiosis patients leads to a significant improvement in the quality of life with no serious complications, and we recommend this to be a standard procedure in resource-poor settings.     

Macrophage participation in the polyclonal and specific response to T-independent antigen in vitro

Effect of adherent cells (macrophages on synthesis of total immunoglobulins (Ig) and specific antibody (Ab) in mice spleen cell culture stimulated by Vi-antigen Salmonella typhi has been studied. Ig and Ab in culture medium were determined by ELISA technique 96 hours after introducing the antigen into cell culture. The adsorption of analysed samples and reference antiserum on antigen coated microplates at pH 3.5 results in reducing nonspecific protein adsorption and promotes quantitative analysis Ab synthesized in vitro. The level of Ab produced in antigen stimulated spleen cell culture during 96 hours after antigen introduction is less than 2% of all synthesized Ig. Removal of most macrophages from spleen cell population results in a considerable decrease of specific and polyclonal immune responses. The basal Ig level in spleen cell culture (without antigen influence) does not decrease after removal of macrophages.