Decreased tuftsin concentrations in patients who have undergone splenectomy

Hyposplenism: A comprehensive review. Part I: Basic concepts and causes

Hyposplenism is not a rare condition and can complicate a remarkable number of illnesses. The two most time-honored diseases associated with the development of hyposplenism are sickle cell anemia and celiac disease. Hyposplenism is relatively easy to recognize by typical changes observed on the peripheral blood smear; including Howell-Jolly bodies, monocytosis, lymphocytosis, and increased platelet counts. Diagnosis can be confirmed by pitted RBC counts or 99Tc-labelled radiocolloid scan of the spleen; wherever available. Diagnosis needs to be made promptly to institute pneumococcal vaccination in a timely fashion and to recognize and treat bacterial infections promptly and aggressively because of the tendency of hyposplenic subject to develop fatal invasive disease. Overwhelming pneumococcal sepsis accounts for the major mortality cases in hyposplenic subjects; however severe infections with other encapsulated bacteria and protozoa have been reported. Hyposplenic individuals may also be at a higher risk for vascular, autoimmune and thrombotic diseases and they may have a higher risk of developing solid tumors. The commonly used pneumococcal polysaccharide vaccine is ineffective in asplenic subjects, because it requires the presence of IgM memory B cells, and should be given before splenectomy. In splenectomized, and functionally hyposplenic subjects, the pneumococcal conjugate vaccine is more effective, because it utilizes a T cell dependent mechanism, and should be the preferred vaccine in these circumstances.

Assessment of splenic function

Hyposplenic patients are at risk of overwhelming post-splenectomy infection (OPSI), which carries mortality of up to 70%. Therefore, preventive measures are warranted. However, patients with diminished splenic function are difficult to identify. In this review we discuss immunological, haematological and scintigraphic parameters that can be used to measure splenic function. IgM memory B cells are a potential parameter for assessing splenic function; however, more studies are necessary for its validation. Detection of Howell-Jolly bodies does not reflect splenic function accurately, whereas determining the percentage of pitted erythrocytes is a well-evaluated method and seems a good first-line investigation for assessing splenic function. When assessing spleen function, (99m)Tc-labelled, heat-altered, autologous erythrocyte scintigraphy with multimodality single photon emission computed tomography (SPECT)-CT technology is the best approach, as all facets of splenic function are evaluated. In conclusion, although scintigraphic methods are most reliable, they are not suitable for screening large populations. We therefore recommend using the percentage of pitted erythrocytes, albeit suboptimal, as a first-line investigation and subsequently confirming abnormal readings by means of scintigraphy. More studies evaluating the value of potentially new markers are needed.

Tuftsin-AZT conjugate: potential macrophage targeting for AIDS therapy

The IgG-derived immunomodulating peptide tuftsin, Thr-Lys-Pro-Arg, is recognized by specific receptors on phagocytic cells, notably macrophages, and is capable of targeting proteins and peptides to these sites. Aiming to target 3'-azido-3'-deoxythymidine (AZT) to HIV-infected macrophages, a conjugate of AZT with tuftsin was synthesized. The AZT-tuftsin chimera possesses the characteristic capacities of its two components. Thus, like AZT, it inhibits reverse transcriptase activity and HIV-antigen expression, and similarly to tuftsin, it stimulates IL-1 release from mouse macrophages and augments the immunogenic function of the cells. Importantly, the conjugate is not cytotoxic to T-cells. The results suggest that the AZT-tuftsin conjugate might have potential use in AIDS therapy.

Effect of liver transplantation on tuftsin activity and phagocytic activity of neutrophil granulocytes in patients with liver cirrhosis

BACKGROUND

Tuftsin activity (TA) is reduced in cirrhosis. This contributes to the defective phagocytic activity (PA) of neutrophil granulocytes and is related to the impairment of splenic function. Orthotopic liver transplantation (OLT) cures cirrhosis and might restore TA. This study was aimed at determining if OLT restores TA and PA.

METHODS

We measured in 9 cirrhotic patients, before and after successful OLT, TA by a bioassay and PA by chemiluminescence in which neutrophils of the patient were tested with both autologous (PA1) and pooled sera from healthy subjects (PA2). Splenic function was assayed by the pitted red cell count.

RESULTS

Before OLT, TA was reduced in 7 patients, and PA1 in all the patients. Pitted cell count was elevated in all the patients. After OLT (median 39 months; range 21-49), TA improved in all cases [median: from 8% (5-16%) to 20% (9-22%), p < 0.008], normalizing in 5 out of the 7 patients with low values. PA1 improved in all the patients [from 102 cpm (65-128 cpm) to 235 cpm (78-280 cpm), p < 0.008], normalizing in 5. Pitted red count decreased in 7 patients and normalized in 3 [from 3.3% (2.1-6.0%) to 2.4% (1.4-2.8%), p < 0.021]. Platelet count [from 55 x 10(3) (30-100) to 185 x 10(3) (93-286), p < 0.008] and leucocyte count [from 3.60 x 10(3) (1.81-5.23) to 5.53 x 10(3) (3.31-6.71), p < 0.008] also improved.

CONCLUSIONS

OLT improves TA and PA of cirrhotic patients. This effect is associated with an improvement of both functional hyposplenism and haematological hypersplenism. The restoration of natural defences against infections may mitigate the adverse effect of immunosuppressive treatment.

Impaired tuftsin activity in cirrhosis: relationship with splenic function and clinical outcome

BACKGROUND

Cirrhotic patients show increased susceptibility to bacterial infections. It is not known whether tuftsin deficiency, which is associated with an increased incidence of infections in many disease states, is present in cirrhosis. Our aims were to determine whether tuftsin activity is deficient in cirrhosis and if so, whether this deficiency is related to splenic function, contributes to altered neutrophil granulocyte function, or influences the occurrence of bacterial infections and patient survival.

METHODS

Tuftsin activity and splenic function were assessed in 31 patients with liver cirrhosis and 31 healthy subjects. The phagocytic activity of neutrophil granulocytes from 23 patients was tested in vitro with addition of both autologous and pooled sera from healthy subjects. In 10 patients and eight controls it was also tested with addition of synthetic tuftsin. Patients were followed up until death or liver transplantation.

RESULTS

Patients had reduced tuftsin activity (median 8% (range 3-24.5)) compared with controls (17% (11.5-37)) (p<0.001) and a higher pitted red cell count (p<0.001). Tuftsin activity was correlated with pitted cell count (p=0.02) and the Child-Pugh score (p=0.002). Nineteen of 23 patients showed deficient phagocytic activity of neutrophil granulocytes, which was correlated with tuftsin activity (p<0.001), improved in all cases but one with addition of serum from healthy subjects, and normalised with addition of synthetic tuftsin. Reduced tuftsin activity did not influence patient survival but was associated with a higher incidence of bacterial infections (p=0.029).

COMMENT

Tuftsin activity was reduced in cirrhosis, and contributed to impaired phagocytic activity of neutrophil granulocytes. Such an abnormality appears to be related to impaired splenic function and severity of cirrhosis, and probably favours the occurrence of bacterial infections.

Autotransplant of spleen tissue in children with schistosomiasis: evaluation of splenic function after splenosis

Autotransplantation of spleen tissue has been done, in the past ten years, in children with schistosomiasis mansoni with bleeding varices. The purposes of this investigation were: (1) to study the morphology and function of the remnant spleen tissue; (2) to quantify the production of tuftsin; and (3) to assess the immune response to pneumococcal vaccine of these patients. Twenty three children, who underwent splenectomy and autologous implantation of spleen tissue into the greater omentum were included in this investigation. The average postoperative follow-up is five years. Splenosis was proved by colloid liver-spleen scans. Search for Howell-Jolly bodies assessed the filtration function. Tuftsin and the titer of pneumococcal antibodies were quantified by ELISA. Splenosis was evident in all children; however, it was insufficient in two. Howell-Jolly bodies were found only in these two patients. The mean tuftsin serum concentration (335.0 +/- 29.8 ng/ml) was inside the normal range. The immune response to pneumococcal vaccination was adequate in 15 patients; intermediate in four; and inadequate in four. From the results the following conclusions can be drawn: splenosis was efficient in maintaining the filtration splenic function in more than 90% and produced tuftsin inside the range of normality. It also provided the immunologic splenic response to pneumococcal vaccination in 65% of the patients of this series.

Infections in E-beta thalassemia

Infection is a major complication and the leading cause of death in thalassemia, especially E-beta thalassemia. The spectrum of infections in E-beta thalassemia include mild and severe infections, therapy-related infections such as Yersinia enterocolitica infection associated with desferrioxamine (DFO) therapy, and transfusion-transmitted disease, as well as unique infections such as with pythiosis. Prospective studies in Thailand indicate that patients with E-beta thalassemia had more frequent episodes of both mild and severe infections. The former included upper respiratory tract infection, acute gastroenteritis, cutaneous abscess, and gingivitis. Severe infections occurred more commonly in patients with splenectomy and included septicemia, pneumonia, biliary tract infection, salmonellosis, and urinary tract infection. Responsible organisms were Escherichia coli (26%), Klebsiella pneumoniae (23%), Salmonella (15%), and Streptococcus pneumoniae (13%). Other organisms included Pseudomonas, Staphylococci, Burkholderia pseudomallei (melioidosis), and Aeromonas. Patients undergoing DFO therapy are at risk for Y. enterocolitica infection which may be localized to mesenteric nodes and tonsils or occur as a generalized form such as septicemia. Recently, we have seen a unique infection so-called vascular pythiosis. Patients usually presented with clinical features of vascular occlusion of lower limbs from ascending arteritis and thrombosis. The causative organism, Pythium insidiosum, is fungus-like, in the kingdom Stramenopila, and in the class Oomycetes. The mortality rate is high and the only effective treatment has been early amputation or possibly immunotherapy. The predisposing factors of infections in thalassemia include splenectomy, iron overload, anemia, and granulocyte dysfunctions. General management of infections in thalassemia consist of prevention, i.e., immunization with pneumococcal and hepatitis vaccines, oral penicillins especially in patients with splenectomy, removal of predisposing factors such as gallstones, iron overload, and appropriate antibiotics.

Splenic autotransplantation after splenectomy: tuftsin activity correlates with residual splenic function

This study set out to determine the relationship between splenic function (as assessed by the percentage of pitted red cells) and tuftsin activity, and to confirm the return of effective splenic function after splenectomy for trauma. Twenty-three patients (13 men) took part. Ten of mean age 48.5 (range 30-74) years had had the spleen removed for traumatic rupture and 13 of mean age 49.7 (range 23-66) years had undergone elective splenectomy. At the time of the study all patients had had the spleen removed a minimum of 1 year previously (mean 6.1 (range 1-15) years). Fifty healthy volunteers matched for sex and age were also studied. In each subject, residual splenic function was evaluated by counting the percentage of pitted red cells. Tuftsin activity was also determined. A highly significant negative correlation was found between pitted red cell percentage and tuftsin activity (rs = -0.80, P < 0.001). Compared with healthy controls (mean 21.6 (range 13-37) per cent), tuftsin activity was significantly reduced both in patients who had undergone splenectomy for trauma (mean 4.4 (range 0-9) per cent; P < 0.0001) and in those who had had elective splenectomy (mean 0; P < 0.0001). Tuftsin activity was significantly (P < 0.001) more depressed after elective than traumatic splenectomy. These data confirm a decrease in tuftsin activity following splenectomy and show that this deficit is significantly greater after elective than emergency removal. These observations confirm that residual splenic function is often present after traumatic splenectomy.

The characteristics of purified HL60 tuftsin receptors

The purification and characteristics of purified HL60 tuftsin receptors are described. Purification was accomplished by affinity chromatography similar to that described earlier, wherein a tuftsin analog Thr-Lys-Pro-Pro-Arg, is covalently linked at the N alpha group to a solid support. The receptor consists presumably of two subunits approximately 66 KDa and 57 KDa. The dissociation constant of the receptor complex is 4.7 X 10(-8) M with 5 X 10(4) receptors per cell. It can form oligomers with an Mr of about 560 KDa suggesting an octomeric structure, assuming the same number of each subunit is associated.

Tuftsin: its chemistry, biology, and clinical potential

Tuftsin is a tetrapeptide, Thr-Lys-Pro-Arg, which resides in the Fc-domain of the heavy chain of immunoglobulin G. The peptide originates from a specific fraction of the parent protein through enzymatic processing. Tuftsin possesses a broad spectrum of activities related primarily to the immune system function and exerts on phagocytic cells, notably on macrophages. These include potentiation of various cell functions such as phagocytosis, motility, immunogenic response, and bactericidal and tumoricidal activities. The features of tuftsin, coupled with its low toxicity, make the peptide an attractive candidate for immunotherapy. Tuftsin's capacity to augment cellular activation is mediated by specific receptors that were identified, characterized, and recently isolated from rabbit peritoneal granulocytes. Tuftsin has been chemically synthesized by a variety of techniques, some of which are adequate for large-scale preparations. A multitude of analogs have also been synthesized and extensively studied for structure-function relationships.

Use of cephalosporins in the immunologically compromised patient

Infection is a major threat to patients with neutropenia, particularly those with haematological malignancies who are undergoing chemotherapy. Early use of an empirical antibiotic regimen with the broadest possible spectrum of activity is recommended until culture data can guide the choice. A standard combination in many centres is an amino-glycoside and a semisynthetic penicillin with antipseudomonal activity or a cephalosporin. However, no regimen can adequately cover all potential pathogens and in these patients, who are exposed to many toxic insults, the choice of antibiotics may significantly increase the incidence of side effects, particularly nephrotoxicity. There has, therefore, been considerable interest in simpler, less toxic (and less expensive) regimens and the concept of monotherapy has been explored. Although recent studies using ceftazidime alone have supported this as an effective approach, there remain several issues to resolve; and on a more cautionary note preliminary results from the latest EORTC study, which recruited more than 1200 patients, suggest that in Gram-negative bacteraemia, conventional combination therapy remains the treatment of choice in neutropenia. While monotherapy is attractive in an environment of low drug resistance when exposure to third generation cephalosporins is infrequent, this is rarely the case. In addition, the widespread use of tunnelled catheters for venous access had led to an increase in Gram-positive infections, and the more intensive immunosuppression to the emergence of fungal infections. Although these tend not to be rapidly fatal, their presence must be considered in designing treatment strategies. The influence of the host and treatment on the type of infection and the relative merits of the differing concepts in therapy are explored in detail in this article.

Splenic function: physiology and splenic hypofunction

A wide variety of disorders can result in diminished splenic function. The pathophysiology appears to be clearly defined in some instances, such as congenital asplenia and disorders of splenic vascular obstruction or congestion. In others, such as the autoimmune and GI disorders, the mechanism remains poorly defined. Further research is needed. The hyposplenia which occurs in many of these disorders has been associated with an increased risk of life-threatening, overwhelming bacterial sepsis. In other instances, this complication has not been reported. This certainly should not be interpreted to mean that it cannot occur. The risk of septicemia in hyposplenic disorders is rarely above 10 to 15%. In disorders with minimal inhibition of splenic function, the incidence of sepsis would presumably be less than the 1.5% incidence following surgical splenectomy for trauma. Considering these data, a very large number of patients would have to become asplenic before it would be likely that one would develop sepsis. Furthermore, the lack of awareness of the possibility of hyposplenia-related sepsis in many of these disorders may cause such occurrences to go unrecognized. Finally, since the risk of sepsis is probably less in hyposplenic adults as compared to children, studies on adults may underestimate the incidence of this complication in children. Many of the disorders reported to cause hyposplenia in adults have not been noted to do so in children. In instances such as celiac disease, it may take many years for the complication to manifest so that it would be unlikely for a child to manifest hyposplenia during childhood. However, in other instances, not enough children have been studied to be confident that the hyposplenia and its associated risk of sepsis are not complications that occur in children. Hyposplenia-related bacterial septicemia is a catastrophic complication. If a patient develops a disorder that is potentially associated with hyposplenia, the patient should be observed for signs of asplenia in the peripheral blood. If the technique is available, quantitation of red cell pits should be performed. If not, other studies of splenic function such as radionuclide scans should be considered, depending on the incidence of hyposplenia in that particular disorder. If evidence of asplenia develops, pneumococcal vaccine should be administered, penicillin prophylaxis should be considered, significant febrile episodes should be managed aggressively, and probably most importantly, the patient and family should be carefully educated about this complication. Most deaths from hyposplenia-related septicemia are preventable.

Impaired neutrophil function in intestinal lymphangiectasia

Impaired neutrophil chemotaxis and phagocytosis were shown in three patients with intestinal lymphangiectasia. Abnormalities in cell associated and serum derived activity occurred, and possible mechanisms are suggested.

Defective activation of neutrophils after splenectomy

Neutrophil chemotaxis and phagocytosis in the presence of serum from 20 patients who had undergone splenectomy and from 15 healthy volunteers was studied. The mean distance migrated by normal neutrophils in the presence of serum from the patients after splenectomy was significantly less than that when normal serum was used (p less than 0.005). The percentage of neutrophils phagocytosing a yeast was also significantly reduced in the presence of serum from patients after splenectomy (p less than 0.02). In addition, when neutrophils from these patients were studied both chemotaxis and phagocytosis were enhanced in normal compared with autologous serum (p less than 0.05).

Immunological consequences of splenectomy

A series of reports have dealt with the occurrence of overwhelming infections in splenectomized patients. Being the largest individual organ of the phagocytic apparatus, the spleen is responsible for the phagocytosis of insufficiently opsonized particles. These are taken up by macrophages, processed, and expressed, together with determinants of the HLA system, on the membrane of the macrophage. T cells recognize these structures and proliferate in response, thus inducing a series of immunoregulatory mechanisms. The anatomic design of the spleen allows for close contact between macrophages and T cells. Thus, splenectomy represents a major intervention into the immunologic system. Splenectomized patients have been shown to have low concentrations of IgM, decreased production of antibodies directed against pneumococci and Escherichia coli, and several defects in cellular immune function, including decreased numbers of T cells and a reduction in lymphocyte proliferative responses. Thus, the removal of the spleen affects certain immunological reactions, which are reflected by a number of clinical findings.

Infection among 210 patients with surgically staged Hodgkin's disease

To determine the incidence and types of infections in Hodgkin's disease, particularly those related to the overwhelming pneumococcal sepsis syndrome, 210 consecutive patients with previously untreated Hodgkin's disease who underwent staging laparotomy with splenectomy from March 1968 to October 1979 were reviewed. For 178 patients (85 percent) alive at the end of the study, the mean follow-up time was 68.1 months. Eighty-two serious infections occurred among 59 (28 percent) of the patients; 47 (57 percent) serious infections were microbiologically documented and 35 (43 percent) were clinically documented. Forty-seven microbiologically documented serious infections occurred in 34 patients and consisted of 23 episodes of pneumonia, 10 cases of bacteremia, seven wound infections, two cases of disseminated herpes zoster, one subphrenic abscess, and four miscellaneous infections. Microbiologically documented serious infections occurring during initial treatment or remission had lower incidences of leukopenia (29 versus 58 percent) (p = 0.09) and death (11 versus 53 percent) (p = 0.005) than those occurring after relapse of Hodgkin's disease. Of the microbiologically documented serious infections, 76 percent were associated with a predisposing factor(s) (leukopenia, postoperative state, steroids, peripheral neuropathy, leukemia), of which 34 percent were fatal. Microbiologically documented serious infections unassociated with a predisposing factor were never fatal, including the only episode of pneumococcal sepsis in the series. In contrast to microbiologically documented serious infections, only 14 percent of clinically documented serious infections (versus 38 percent) were fatal. The overwhelming pneumococcal sepsis syndrome and other infections thought to be associated with the asplenic state are uncommon problems in patients with Hodgkin's disease after splenectomy.

Reticuloendothelial function in coeliac disease and ulcerative colitis

Patients with ulcerative colitis and coeliac disease who had been shown by impaired clearance of heat damaged red cells to have diminished splenic phagocytosis, were examined for evidence of more generalised reticuloendothelial malfunction by measuring their circulatory clearance of micro-aggregated albumin. Although in animals micro-aggregated albumin is largely removed by Kupffer cells, we found impaired clearance in otherwise normal subjects who had previously had surgical splenectomy. In patients with hyposplenism because of bowel disease there was no additional impairment of micro-aggregated albumin clearance, indicating that their hyposplenism is an isolated phenomenon and not part of a generalised reticuloendothelial atrophy. Patients with coeliac disease and normal splenic function had increased reticuloendothelial catabolic activity; this was not present in patients with coeliac disease and abnormal splenic function.

Overwhelming postsplenectomy sepsis in childhood

Three hundred ninety-three splenectomies were performed within the Charity Hospital system during the decade from 1969 through 1979. This number included 56 operations in children under 16 years of age, which formed the basis of this report of the risk of infection in young splenectomized patients and provided guidelines for the role of splenectomy under emergency and elective conditions. Eight episodes of serious infection were documented in four patients. There was only one case of overwhelming postsplenectomy infection which resulted in death, for a mortality rate of 1.8 percent (1 of 56 children) for death due to overwhelming postsplenectomy sepsis. It is emphasized, however, that the development of serious postsplenectomy sepsis in our series resulted in a 25 percent mortality rate. The risk of postsplenectomy sepsis is much greater in those individuals who are immunologically compromised, such as those who undergo staging splenectomy for Hodgkin's disease. If splenectomy is indicated for a hematologic disorder, it is wise to defer operation for as long as possible, especially if the acute episodes are self-limiting or mild. Rather than the promiscuous use of polyvalent serum and antibiotic therapy after splenectomy in children, it is recommended that parents be advised to bring the child to the hospital anytime an illness or fever develops that might require an immediate loading dose of an appropriate antibiotic. The role of subtotal splenectomy or hemisplenectomy merits consideration in staging Hodgkin's disease. Preoperative study of certain immunologic parameters may provide guidelines as to the proportion of individuals who may be vulnerable to overwhelming sepsis after splenectomy.

Complement studies in splenectomized patients

Total haemolytic complement activity, C2, C5, total alternative pathway activity, factor B, and C3d were measured in 85 splenectomized patients from 1 month to 32 years after splenectomy. Furthermore the patients were investigated for circulating immune complexes. No major deficiencies of the complement factors were detected. In a few patients a reduced C2 level was caused by genetically determined defects or was due to complement consumption in conjunction with circulating immune complexes. The complement levels were normal in 2 patients who had survived overwhelming infections after splenectomy. C5 was elevated in a major proportion of the patients, and it is suggested that this might be caused by post-splenectomy monocytosis. Circulating immune complexes were found in 20% of all cases, irrespective of the presence of residual splenic tissue. Thus the commonly cited impairment of the complement system after splenectomy does not seem to be substantiated, and the deficient resistance against bacterial infections in splenectomized patients does not seem to include abnormalities of the complement system.

Antibody response and opsonization afer pneumococcal vaccination in splenectomized children and healthy persons

A significant rise in antibody against pneumococcal types 3, 6A and 25 after pneumococcal vaccination could be demonstrated in 26 of 30 individuals (87%) using an enzyme-linked immunosorbent assay. Similar geometric mean antibody fold increases were found in splenectomized children, non-splenectomized children and healthy adults for types 6A and 25. Splenectomized children exhibited a somewhat lower, but not statistically significant, geometric mean antibody fold increase against type 3 (p = 0.10), as compared to non-splenectomized children. For the whole group a negative correlation could be demonstrated between prevaccination antibody concentration and antibody fold increase after vaccination. After vaccination an enhanced serum opsonic activity against type 3 was found by granulocyte glucose-l-14C oxidation for the whole group of 30 patients (p less than 0.05) but nine individual patients (30%) failed to exhibit an increase. No differences between the three patient groups were demonstrable. Changes in serum opsonic activity could not be detected by a pneumococcal bactericidal assay.

Antibody response to pneumococcal vaccine in splenectomized adults and adolescents

The antibody response of 67 splenectomized adults and adolescents with benign underlying diseases to a 14-valent pneumococcal capsular polysaccharide vaccine was determined by an enzyme-linked immunosorbent assay. It was not significantly different from that of 12 healthy non-splenectomized adult volunteers for 13 of the 14 polysaccharide antigens studied. Residual splenic tissue as detected by Tc-scintigraphy was without any influence on the vaccination response. In comparison 5 untreated splenectomized adults with malignant diseases and 11 splenectomized adults receiving immunosuppressive therapy exhibited a significantly reduced combined geometric mean of their postvaccination antibody concentrations (all 14 antigens added) and of their combined geometric mean antibody fold increase as compared to the healthy non-splenectomized adults. The reduction in antibody response was most pronounced in the group of immunosuppressed patients. Immunogenicity of each of the 14 vaccine antigens varied considerably as judged by the geometric means of the postvaccination arbitrary antibody concentrations. Also individual variation in postvaccination antibody concentration against each antigen was large.

Tuftsin, Thr-Lys-Pro-Arg. Anatomy of an immunologically active peptide

Tuftsin, a natural occurring tetrapeptide, has been found to exhibit several biological activities connected with immune system function. Although little is known about tuftsin's 'biogenesis', much information has been gleaned about its structure-function relationships, which have shown that several features of the molecule are essential for expression of full biological activity. Furthermore, specific receptor sites for tuftsin have been found to exist exclusively on phagocytic cells. Research indicates that tuftsin binding to target cells effect intracellular calcium and cyclic nucleotide levels. Implication of these facts on tuftsin's mode of action are discussed. Basic peptidic segments resembling tuftsin are found in a variety of regulatory peptides. Questions are, therefore, raised as to the biospecificity an cross-reactivity of these sequences. Substance P, one such peptide, which binds with and activates tuftsin receptors, is described. In light of tuftsin's therapeutic potential, assays for its determination have been introduced. When applied to analyze human blood serum of normal as well as of various pathological origins, direct correlation was found between tuftsin levels and susceptibility to bacterial infections.

Monocyte cytotoxicity after splenectomy

Antibody-dependent cell-mediated cytotoxicity (ADCC) by monocytes was determined in 45 adults approximately 4 years after splenectomy for either abdominal trauma or accidental injury during operation for benign gastroduodenal ulcer. Compared to controls, both groups of splenectomized persons showed increased numbers of monocytes and decreased monocyte ADCC. The decrease of monocyte ADCC was only significant in those splenectomized persons in whom accessory splenic tissue was not detectable by isotope scanning. Addition of the spleen-dependent peptide tuftsin to monocytes in vitro did not augment their ADCC. An increase serum concentration of immune complexes was neither related to the presence of splenic tissue nor to the monocyte cytotoxicity. Vaccination with pneumococcal polysaccharide had no effect on monocyte ADCC. It is suggested that the defective monocyte cytotoxicity observed in splenectomized persons without detectable splenic tissue might be relevant to post splenectomy infectious susceptibility.

Surgery alone or combined with radiation therapy in esophageal carcinoma

Two patient-materials with esophageal carcinoma are analyzed: a group of 22 patients who, during the period 1971-1974, were treated with esophageal resection followed by esophagogastrostomy or colonic interpolation; a second group of 28 patients from 1975-1978, who were treated in the same way, but also given either preoperative or postoperative radiation therapy, or both. Surgical mortality was about the same in the two groups: 25-32%. The group given radiation therapy had a one-year survival rate of 50%, as compared with 23% in the group treated solely with surgery. All 24 patients given combined therapy, with all or part of the absorbed dose of 24-47 Gy given preoperatively, showed vital cancer in resected specimens. Vital cancer was found in the periesophageal nodes in only six patients (25%), however; patients given no preoperative radiation therapy had tumor in 20 of 26 cases (77%; P less than 0.01). Celiac nodes were resected at laparotomy; when malignancy was found, the celiac region was irradiated postoperatively. This finding does not appear to exclude long-term survival, as two patients with metastases to the celiac nodes at operation are alive 16 and 20.5 months following surgery. Simple compared to troublesome dissection gives a better rate of survival. The spleen was unintentionally injured in 21 patients at laparotomy and had to be removed. One-year survival was better in patients with intact spleen, especially in those who also had radiation therapy. Patients with resected spleen succumbed from metastases more often than from mediastinal recurrence, as compared with the patients with intact spleen.

Detection of splenosis and ectopic spleens with 99mTc-labelled heat damaged autologous erythrocytes in 90 splenectomized patients

Splenosis or ectopic spleens were detected in 22 of 45 patients splenectomized after either abdominal trauma or accidental lesions of the spleen during operation. The incidence of ectopic spleen tissue in various groups of splenectomized patients has been investigated by a sensitive scanning method employing reinjection of 99mTc-labelled heat damaged autologous erythrocytes. In comparison 7 cases were found among 45 patients who underwent splenectomy for haematological reasons. The time span between the operation and a positive scan varied between 3 months and 11 years. None of the patients in the haematological group with reoccurrence of spleen tissue presented any signs of relapse of their primary disorder. The only patient with overwhelming infection was a girl in whom splenectomy was performed for hereditary spherocytosis. She recovered from the sepsis and her scan was negative. It is concluded that recurrence of spleen tissue is frequent after traumatic lesions of the spleen but rare after selective splenectomy for haematological reasons. This may account for the lesser tendency to overwhelming sepsis after post-traumatic splenectomy.

Spleen scanning with 99Tcm-labelled red blood cells after splenectomy

In order to correlate the haematological changes which occur after splenectomy, with the presence or absence of residual splenic tissue, spleen scans using 99Tcm-labelled red blood cells were performed in 36 patients who had had a splenectomy. Positive spleen scans were found in 44 per cent (8 out of 18) of patients who had undergone splenectomy for trauma and in 17 per cent (3 out of 18) of patients who had undergone elective splenectomy. No relationship was found between the presence of Howell-Jolly bodies, platelet counts, the levels of IgG, IgM and IgA and the scan result. It is concluded that these findings are due to the presence of splenunculi, whose incidence is more common than the 12 per cent usually quoted.

[Alterations of humoral and cellular immunity after splenectomy (author's transl)]

In twenty-seven splenectomized patients, who had undergone splenectomy for trauma (n=13) and thirty-one immunologically healthy persons, matched for age and sex, the following immunological parameters were examined: Serum immunoglobulins M, A, G, D and E, complement factors C3, C4 and the serum haemolytic complement activity (Ch 50), as well as the ratio and in vitro reagibility of B-and T-lymphocytes measured by transformation responses to the non-specific mitogens Phytohämagglutinin, Concanavalin A and Pokeweed-Mitogen. The phagocytic capacity of polymorphonuclear neutrophils was tested by the Nitroblue tetrazolium test. Total peripheral lymphocytes, B- und T-lymphocytes from splenectomized patients were significantly higher than in healthy controls (p less than 0.01). The PHA response in splenectomized patients was significantly depressed (p less than 0.01) as compared to nonsplenectomized controls. Also IgM serum concentration was found to be significantly lower in these patients (p less than 0.01). No differences were observed between patients, who had been splenectomized 7 months to 5 years or 6 to 14 years ago. The comparison of persons splenectomized for traumatological or haematological disorders showed statistically no significant differences. The importance of the spleen for the primary immune response is discussed.

Late sequelae of splenectomy for trauma

Hematologic and immunologic changes following splenectomy for trauma include abnormal RBC morphology, leukocytosis, thrombocytosis, impaired clearance of blood-borne particulate antigens, and reduced antibody formation. These abnormalities may be the bases for overwhelming bacterial infection, the most serious delayed complication of splenectomy for trauma. The state of knowledge at present indicates that splenectomized patients should receive pneumococcal vaccination, but whether penicillin prophylaxis should be given daily in addition is less clear. However, penicillin may be advisable for young children, particularly those under 2 years of age, in whom the efficacy of pneumococcal vaccine has not been established. To prevent sepsis, various surgical alternatives to total splenectomy have been proposed, including deliberate autotransplantation of splenic tissue at the time of splenectomy.

Decreased serum tuftsin concentrations in sickle cell disease

The serum concentrations of the phagocytosis-stimulating peptide, tuftsin, were determined by radioimmunoassay in 21 patients with sickle cell disease and in 12 healthy controls. The mean serum tuftsin concentration was significantly lower in patient with haemoglobin SS disease (154.3 +/- 35.1 ng/ml; 308.6 +/- 70.2 nmol/l, P < 0.01) and in patients with haemoglobin SC and CC disease (180.9 +/- 42.7 ng/ml; 361.8 +/- 85.4 nmol/l, P < 0.05) than in healthy controls (228.7 +/- 46.7 ng/ml; 457.4 +/- 93.4 nmol/1). Tuftsin deficiency is an indicator of splenic hypofunction and may contribute to the increased susceptibility of patients with sickle cell disease to severe infection.

Polymorphonuclear neutrophil function in malignant lymphomas and effects of splenectomy

Granulocyte (PMN) directional locomotion (migration) in vitro and in vivo, resting nitroblue tetrazolium (NBT)-reduction and adherence to nylon wool of polymorphonuclear neutrophils (PMN) were assayed in 7 patients with Hodgkin's disease (HD) and in 11 patients with non-Hodgkin's lymphoma (NHL) prior to therapy. In most patients with HD, NBT-reduction was increased and in all directional locomotion was markedly decreased both in vitro and in vivo. In addition to being depressed, accumulation of PMN into skin chambers in patients with HD correlated with the peripheral blood count (r = 0.95). In vitro directional migration of PMN in NHL was depressed in half the patients, but increased in the in vivo assay. After splenectomy, PMN-adherence tended to increase and NBT-reduction to decrease. These findings are compatible with a constant cellular defect of PMN in HD, whereas in NHL abnormal PMN function is more likely mediated by extracellular factors. Abnormal PMN function may correlate with clinical susceptibility to infection in malignant lymphomas.

The clinical and physiological aspects of tuftsin deficiency syndromes exhibiting defective phagocytosis

The tetrapeptide tuftsin (Thr-Lys-Pro-Arg) stimulates phagocytosis by blood neutrophilic granulocytes and tissue macrophages in a highly specific manner. Tuftsin is cleaved off the carrier gamma-globulin molecule as the free active form by two enzymes. One of these is in the spleen and the other on the outer membrane of the phagocyte. Congenital tuftsin deficiency usually arises when the peptide is mutated to an inactive peptide. The acquired type occurs if the spleen function is curtailed by removal or disease. Tuftsin deficiency is manifested by severe recurrent infections involving primarily the skin, lymph nodes and lungs. Therapy is limited to gamma-globulin injection along with appropriate chemotherapy.

Splenic function: normal, too much and too little

This review is concerned with normal splenic function, mechanisms and consequences of splenomegaly, hypersplenism, the medical indications for splenectomy and the various aspects of hyposplenism. The potential probelm of lethal septicemia in hyposplenic or asplenic patients is also considered.