Isolation of a cDNA encoding a human serum marker for acute pancreatitis. Identification of pancreas-specific protein as pancreatic procarboxypeptidase B

Ambush predation and the origin of euprimates

Primates of modern aspect (euprimates) are characterized by a suite of characteristics (e.g., convergent orbits, grasping hands and feet, reduced claws, and leaping), but the selective pressures responsible for the evolution of these euprimate characteristics have long remained controversial. Here, we used a molecular phyloecological approach to determine the diet of the common ancestor of living primates (CALP), and the results showed that the CALP had increased carnivory. Given the carnivory of the CALP, along with the general observation that orbital convergence is largely restricted to ambush predators, our study suggests that the euprimate characteristics could have been more specifically adapted for ambush predation. In particular, our behavior experiment further shows that nonclaw climbing can significantly reduce noises, which could benefit the ancestral euprimates' stalking to ambush their prey in trees. Therefore, our study suggests that the distinctive euprimate characteristics may have evolved as their specialized adaptation for ambush predation in arboreal environments.

Molecular phyloecology suggests a trophic shift concurrent with the evolution of the first birds

Birds are characterized by evolutionary specializations of both locomotion (e.g., flapping flight) and digestive system (toothless, crop, and gizzard), while the potential selection pressures responsible for these evolutionary specializations remain unclear. Here we used a recently developed molecular phyloecological method to reconstruct the diets of the ancestral archosaur and of the common ancestor of living birds (CALB). Our results suggest a trophic shift from carnivory to herbivory (fruit, seed, and/or nut eater) at the archosaur-to-bird transition. The evolutionary shift of the CALB to herbivory may have essentially made them become a low-level consumer and, consequently, subject to relatively high predation risk from potential predators such as gliding non-avian maniraptorans, from which birds descended. Under the relatively high predation pressure, ancestral birds with gliding capability may have then evolved not only flapping flight as a possible anti-predator strategy against gliding predatory non-avian maniraptorans but also the specialized digestive system as an evolutionary tradeoff of maximizing foraging efficiency and minimizing predation risk. Our results suggest that the powered flight and specialized digestive system of birds may have evolved as a result of their tropic shift-associated predation pressure.

Mutations in the pancreatic secretory enzymes CPA1 and CPB1 are associated with pancreatic cancer

To evaluate whether germline variants in genes encoding pancreatic secretory enzymes contribute to pancreatic cancer susceptibility, we sequenced the coding regions of CPB1 and other genes encoding pancreatic secretory enzymes and known pancreatitis susceptibility genes (PRSS1, CPA1, CTRC, and SPINK1) in a hospital series of pancreatic cancer cases and controls. Variants in CPB1, CPA1 (encoding carboxypeptidase B1 and A1), and CTRC were evaluated in a second set of cases with familial pancreatic cancer and controls. More deleterious CPB1 variants, defined as having impaired protein secretion and induction of endoplasmic reticulum (ER) stress in transfected HEK 293T cells, were found in the hospital series of pancreatic cancer cases (5/986, 0.5%) than in controls (0/1,045, P = 0.027). Among familial pancreatic cancer cases, ER stress-inducing CPB1 variants were found in 4 of 593 (0.67%) vs. 0 of 967 additional controls (P = 0.020), with a combined prevalence in pancreatic cancer cases of 9/1,579 vs. 0/2,012 controls (P < 0.01). More ER stress-inducing CPA1 variants were also found in the combined set of hospital and familial cases with pancreatic cancer than in controls [7/1,546 vs. 1/2,012; P = 0.025; odds ratio, 9.36 (95% CI, 1.15-76.02)]. Overall, 16 (1%) of 1,579 pancreatic cancer cases had an ER stress-inducing CPA1 or CPB1 variant, compared with 1 of 2,068 controls (P < 0.00001). No other candidate genes had statistically significant differences in variant prevalence between cases and controls. Our study indicates ER stress-inducing variants in CPB1 and CPA1 are associated with pancreatic cancer susceptibility and implicate ER stress in pancreatic acinar cells in pancreatic cancer development.

Phosphorylation of carboxypeptidase B1 protein regulates β-cell proliferation

A reduction in pancreatic islet β-cells leads to the onset of diabetes. Hence, the identification of the mechanisms inducing β-cell proliferation is important for developing a treatment course against the disease. It has been well established that post-translational modifications (PTMs) of proteins affect their functionality. In addition, PTMs have been suggested to play important roles in organ regeneration. Therefore, in this study, we investigated PTMs associated with pancreatic regeneration using two-dimensional electrophoresis. Four carboxypeptidase B1 (CPB1) proteins were identified at different isoelectric points, with the same molecular weight. The motif of CPB1 PTMs was identified by mass spectrophotometry, and the downregulation of CPB1 phosphorylation in pancreatectomy was confirmed. The dephosphorylation of CPB1 induced β-cell proliferation. We thus surmise that the altered PTM of CPB1 is associated with pancreatic regeneration.

Poly(adenylic acid) complementary DNA real-time polymerase chain reaction in pancreatic ductal juice in patients undergoing pancreaticoduodenectomy

OBJECTIVES

There is a need to develop methods of early diagnosis for pancreatic cancer. Pancreatic juice is easily collected by endoscopic retrograde cholangiopancreatography and may facilitate diagnosis using molecular markers. The aim of this work was to explore the feasibility of measurement of gene expression in RNA isolated from ductal juice.

METHODS

Intraoperative sampling of pancreatic juice was undertaken in 27 patients undergoing pancreaticoduodenectomy for suspected tumor. Total RNA was extracted and used as template for poly(adenylic acid) (poly[A]) polymerase chain reaction (PCR) to generate a globally amplified complementary DNA pool representative of all expressed messenger RNAs. Real-time PCR was performed for trefoil factor 2 (TFF2), carboxypeptidase B1 (CPB1), and kallikrein-related peptidase 3 (KLK3) in a subset of samples; all samples were normalized for 3 reference genes (glyceraldehyde-3-phosphate dehydrogenase [GAPDH], PSMB6, and beta-2-microglobulin [B2M]).

RESULTS

The median volume of the pancreatic juice obtained was 1245 microL (range, 50-5000 microL). The RNA integrity number ranged from 1.9 to 10. Reverse transcriptase PCR was positive for pancreas-specific genes (TFF2 and CPB1) and negative for prostatic-specific antigen in all samples.

CONCLUSIONS

These results demonstrate that RNA analysis of pancreatic juice is feasible using a combination of poly(A) PCR and real-time PCR. In addition, the poly(A) complementary DNA generated can be probed for multiple genes and is indefinitely renewable, thereby representing a molecular block of importance for future research.

cpbAg1 encodes an active carboxypeptidase B expressed in the midgut of Anopheles gambiae

We previously used differential display to identify several Anopheles gambiae genes, whose expression in the mosquito midgut was regulated upon ingestion of Plasmodium falciparum. Here, we report the characterization of one of these genes, cpbAg1, which codes for the first zinc-carboxypeptidase B identified in An. gambiae and in any insect. Expression of cpbAg1 in baculovirus gave rise to an active enzyme, and determination of the N-terminal amino acids confirmed that CPBAg1 contains a signal peptide and a pro-peptide, typical features of digestive zinc carboxypeptidases. cpbAg1 mRNA was mainly produced in the mosquito midgut, where it accumulated in unfed females and was rapidly down-regulated upon blood feeding. Annotation of the An. gambiae genome predicts twenty-three sequences coding for zinc-carboxypeptidases of which only two (cpbAg1 and cpbAg2) are expressed at a significant level in the mosquito midgut.

The intrinsic threshold of the fibrinolytic system is modulated by basic carboxypeptidases, but the magnitude of the antifibrinolytic effect of activated thrombin-activable fibrinolysis inhibitor is masked by its instability

Activated thrombin-activable fibrinolysis inhibitor (TAFIa) is intrinsically unstable, a property that complicates the study of its role in regulating fibrinolysis. To investigate the effect of basic carboxypeptidases on fibrinolysis under conditions of constant carboxypeptidase activity, we employed pancreatic carboxypeptidase B (CPB), a homologous, stable basic carboxypeptidase, as a surrogate for TAFIa. Clots formed from TAFI-depleted plasma or from purified components were supplemented with tissue-type plasminogen activator and either CPB or TAFIa. The clot lysis data indicate that the down-regulation of fibrinolysis mediated by basic carboxypeptidases involves a threshold mechanism. At carboxypeptidase concentrations above the threshold, plasminogen activation is maintained in a fully down-regulated state; experiments in plasma showed that fibrinolysis is essentially halted by saturating concentrations of TAFIa and that fibrinolysis can be prolonged more than 45-fold by a stable carboxypeptidase. The threshold carboxypeptidase concentration was dependent on tissue-type plasminogen activator and antiplasmin concentrations, indicating that the threshold is determined by the steady-state plasmin concentration. Although obvious with CPB, the threshold was masked by the intrinsic instability of TAFIa and became apparent only when the effect of TAFIa was investigated over the picomolar concentration range. Because of the threshold effect and the instability of TAFIa, exponential increases in TAFIa concentration generate linear increases in lysis time. A model relating lysis time to TAFIa concentration, TAFIa half-life, and the threshold concentration of TAFIa is provided. The threshold effect has potentially important implications regarding the role of TAFIa and the regulation of clot lysis in vivo.

Molecular cloning and cDNA sequence analysis of carboxypeptidases A1, A2 and B from the Japanese flounder Paralichthys olivaceus

Although pancreatic serine proteases have been cloned in teleosts, no sequence data are currently available on members of the carboxypeptidase (CP) family. Here, we cloned cDNAs coding for two preproCPAs, corresponding to mammalian preproCPA1 and preproCPA2, and one preproCPB from a pancreatic cDNA library of the Japanese flounder, Paralichthys olivaceus. The activation peptides of flounder proCPs completely retained the sequences for inhibition of enzymatic activity of proCPs just like mammalian proCPs. Of 306-309 amino acids in total, 95 amino acids are completely conserved between bovine CPA1 and CPB and flounder CPs. Notably, amino acid residues for Zn(2+) ligands, catalysis and substrate anchoring are completely conserved between flounder and bovine CPs. Three species of flounder preproCPs are all expressed in the pancreas of first feeding larvae.

The usefulness of laboratory tests in the early assessment of severity of acute pancreatitis

Acute pancreatitis is a disorder that affects approximately 200,000 individuals in the U.S. annually. While most cases are mild, up to 30% of patients will have a complicated course with prolonged hospitalization and significant morbidity and mortality. Early institution of several therapeutic interventions, such as enteral nutrition, prophylactic antibiotics, endoscopic retrograde cholangiopancreatography (ERCP) and intensive care monitoring, have been shown to decrease the morbidity associated with severe acute pancreatitis. However, the ability of clinicians to predict, upon presentation, which patient will have mild or severe pancreatitis has remained poor over the years, thus leading to a delay in the institution of such treatments. Researchers have focused on markers that might improve upon clinical prediction alone. While data have shown the predictive value of tools such as Ranson's and Glasgow's criteria, C-reactive protein (CRP) and the APACHE score, their application in clinical practice has been limited by a time delay of at least 48 h in the former two and by being cumbersome in the latter. Thus, our focus is to critically appraise the evidence available for various biochemical markers in their ability to distinguish mild and severe acute pancreatitis early and more accurately than currently available tools.

Expression of human brain carboxypeptidase B, a possible cleaving enzyme for beta-amyloid precursor protein, in peripheral fluids

Human brain carboxypeptidase B (HBCPB) is a novel brain protease that processes native brain beta-amyloid precursor protein (APP) in vitro. Immunoblot analysis of human serum and cerebrospinal fluid (CSF) using anti C14-module antibody, which recognizes the C-terminal peptide unique to HBCPB, detected the 30 and 40 kDa immunoreactive bands. Analysis of HBCPB prepared from both serum and CSF demonstrated proteolytic activities for brain APP. Protease inhibitor spectrum analysis also supports that these bands correspond to the mature form and and prepro form of HBCPB, respectively. As is the case in brain parenchyma, the prepro-form is dominant in CSF. In serum, however, the majority of HBCPB exists in the mature form, possibly due to an abundant trypsin-like proteolytic activity in serum. HBCPB expressed in serum and CSF, therefore, may have a significance as a peripheral marker of the brain protease, which participates in APP processing in human brain.

A novel carboxypeptidase B that processes native beta-amyloid precursor protein is present in human hippocampus

The processing of beta-amyloid precursor protein (APP) and generation of beta-amyloid (Abeta) are associated with the pathophysiology of Alzheimer's disease (AD). As the proteases responsible for the process in the human brain have yet to be clarified, we have searched for activities capable of cleaving native brain APP in the human hippocampus. A 40-kDa protein with proteolytic activity that degrades native brain APP in vitro was purified and characterized; molecular analysis identified it as a novel protease belonging to the carboxypeptidase B (CPB) family. PC12 cells overexpressing the cDNA encoding this protease generate a major 12-kDa beta-amyloid-bearing peptide in cytosol, a peptide which has also been detected in a cell-free system using purified brain APP as substrate. Although the protease is homologous to plasma CPB synthesized in liver, it has specific domains such as C-terminal 14 amino acid residues. Western analysis, cDNA-cloning process and Northern analysis suggested a brain-specific expression of this protease. An immunohistochemical study showed that the protease is expressed in various neuronal perikarya, including those of pyramidal neurons of the hippocampus and ependymal-choroid plexus cells, and in a portion of the microglia of normal brains. In brains of patients with sporadic AD, there is decreased neuronal expression of the protease, and clusters of microglia with protease immunoreactivity associated with its extracellular deposition are detected. These findings suggest that brain CPB has a physiological function in APP processing and may have significance in AD pathophysiology.

Proteins expressed by pancreatic duct cells and their relatives

Significant progress has been made in the characterization of the structure and function of pancreatic ductal cells. Our understanding at this point in time extends to knowledge of specific molecules that provide for the structural composition of the ductal cells, their interactions with the local environment, and the regulation of their growth and properties of differentiation. Knowledge of the molecular composition and structure of the secretory products of epithelial cells in the pancreas also has increased so that we now understand the individual contributions of several secretory products to the overall function of pancreatic juice. Further study of these parameters will give us important insight into the normal function of the ductal cells and into how these processes are altered during the development and progression of diseases of the pancreas such as pancreatitis and cancer.

Alcohol and the pancreas

Alcoholic pancreatitis may be one of the most serious adverse consequences of alcohol abuse. Its diagnosis, as it has for many years, depends primarily on clinical acumen in interpreting properly the symptoms and signs of abdominal distress, buttressed by elevated pancreatic enzymes (amylase and lipase). More recently, the use of computerized tomography (CT) in selected situations has been both of confirmatory and prognostic value. Severity of abnormality by CT correlates reasonably well with a variety of clinical-laboratory clusters (APACHE system, Ranson's criteria, etc.) and aids in therapy. The pathogenesis of alcoholic pancreatitis is not fully defined. The ultimate picture is one of tissue autolysis by activated proteolytic enzymes. The triggers for such activation, however, are still not known. They are represented by three main theories: (1) large duct obstruction and/or increased permeability relative to pancreatic secretion, (2) small duct obstruction due to proteinaceous precipitates, and (3) a direct toxic-metabolic effect of ethanol on pancreatic acinar cells. While not mutually exclusive, we favor the last hypothesis as being most consistent with the effects of ethanol on other organ systems. The direct effects of ethanol and/or its metabolites may be mediated, at least in part, via oxidative stress or the generation of fatty acid ethyl esters. Autolysis (regardless of proximate mechanism(s)) leads to inflammation likely mediated via release of various cytokines. It also should be appreciated that "acute" pancreatitis (the topic of this chapter) likely represents an acute process within a chronic pancreatic exposure and injury from alcoholic abuse. The key question of why pancreatitis develops in only a small number of alcohol abusers is not resolved. Therapy depends on the severity of alcoholic pancreatitis, which is defined by clinical-laboratory and often CT criteria. Mild pancreatitis usually resolves acutely with alcohol abstention and supportive therapy. Severe pancreatitis has a significant morbidity and mortality, mainly related to the degree of pancreatic necrosis and infection. It requires meticulous combined medical-surgical care.

Studies on the turnover of procarboxypeptidase B, its active enzyme and the activation peptide in the pig

Recent developments in the treatment of acute pancreatitis have focused on the importance of early determination of the severity of an attack. Measuring levels of activation peptides from pancreatic proenzymes seems to be one way to predict severity. Levels of the activation peptide from procarboxypeptidase B, in both serum and urine on admission, have been shown to correlate to the outcome. To be able to interpret levels of this peptide in serum and urine under normal and in various acute abdominal conditions, we need knowledge about its turnover in the circulation. Procarboxypeptidase B, active carboxypeptidase and the activation peptide were therefore purified from porcine pancreatic juice. These proteins were labelled with 125I or 131I and their turnovers were studied in vivo in the pig. The proenzyme and the activation peptide were eliminated without interaction with any substance in the circulation. The active enzyme was to some degree bound to a substance with a molecular mass of 10-20 kDa. Active CPB was eliminated more slowly than proCPB and the activation peptide. Five percent of the activation peptide was detected nondegraded in the urine. After intraduodenal administration of the activation peptide there was no sign of the peptide in the urine.

Evaluation of three pancreas specific protein assays, TLI(trypsin-like immunoreactivity), PASP (pancreas specific protein) and CA 19-9 (glycoprotein) for use in the diagnosis of canine pancreatitis

Three radioimmunoassays (RIA) for the pancreas specific proteins TLI, PASP and CA 19-9 were evaluated in serum from normal control dogs (n = 40) and dogs with pancreatitis (n = 20). Statistically significant differences (P < 0.05) were found for serum TLI and PASP levels between the control and pancreatitis groups. However, only 3/20 dogs with pancreatitis had serum TLI concentrations greater than the highest concentration in control dogs. Concentrations of PASP in serum were higher in 15/20 dogs with pancreatitis than in the control dogs. The magnitude of the increase in concentrations of PASP in pancreatitis was small in the majority of cases. Thus these assays are of limited clinical value in the diagnosis of pancreatitis. There was no cross-reactivity with dog serum in the CA 19-9 assay.

Human pancreas-specific protein. A diagnostic and prognostic marker in acute pancreatitis and pancreas transplantation

CONCLUSION

Human pancreas-specific protein (hPASP) is a very sensitive reflector of the extent of pancreatic necrosis on the cellular level, and is of both diagnostic and prognostic value in acute pancreatitis. Furthermore, it allows the estimation of the severity of graft pancreatitis soon after simultaneous renal and pancreatic transplantation.

BACKGROUND

Diagnosis of acute pancreatitis (AP) has been improved in the past 15 yr as new methods for the determination of specific pancreatic enzymes have been developed. However, these enzymes have no prognostic implications. In this prospective study, we evaluated the role of human pancreas-specific protein (hPASP) in comparison with pancreatic amylase and C-reactive protein (CRP) in acute pancreatitis and pancreas transplantation.

PATIENTS AND METHODS

The study included 40 patients (22 female, 18 male; mean age 51 yr, range 22-88 yr) with AP and 7 patients (2 female, 5 male; mean age 37 yr, range 25-49 yr) with type I diabetes and renal insufficiency who underwent simultaneous kidney and pancreas transplantation. By means of contrast-enhanced computed tomography (CT) and/or intraoperative findings, patients were judged to have edematous-interstitial (AIP, n = 20, mean age 55.2 yr, range 24-88 yr) or necrotizing pancreatitis (NP, n = 20, mean age 46.3 yr, range 22-81 yr). Serum hPASP concentration was measured daily by a commercial radioimmunoassay technique. In 25 healthy subjects and in several control groups (35 patients with chronic pancreatitis, 20 patients with pancreatic carcinoma and 80 patients with different gastrointestinal diseases) a single blood specimen was taken at hospital admission for the determination of the normal range of hPASP and for specificity analysis.

RESULTS

The upper normal value for hPASP in healthy subjects was found to be 52 ng/mL. Serum hPASP was elevated in all patients suffering from AP, with a median of 343 ng/mL (lower-upper quartile: 192-478 ng/mL) at hospital admission. In the daily serum monitoring with respect to the onset of symptoms, significantly higher hPASP levels were found in NP compared with AIP after day 2 (p < 0.001). In patients with NP, peak values of hPASP correlated significantly with the extent of pancreatic necroses measured by contrast-enhanced CT-scanning, whereas CRP did not. Six patients of the transplantation group had the same serum hPASP course as AIP, with almost normal values on the third postoperative day. One patient had elevated levels throughout the observation period. This patient suffered from necrotizing graft pancreatitis, confirmed by relaparotomy, and died because of subsequent septic complications.

Serum procarboxypeptidase B, amylase and lipase in chronic renal failure

Procarboxypeptidase B (human pancreas-specific protein) has been reported to be a good serum marker for the diagnosis of acute pancreatitis. The current study was conducted in order to evaluate the frequency and degree of elevated serum levels of procarboxypeptidase B in chronic renal failure and their correlations with serum levels of amylase, lipase and renal function tests. Blood samples were taken from 84 asymptomatic patients with chronic renal failure, including 34 patients with periodical haemodialysis and 50 patients without haemodialysis. Serum levels of procarboxypeptidase B, amylase, lipase, creatinine and blood urea nitrogen were measured. Serum levels of procarboxypeptidase B in 84 patients were 63.4 +/- 5.5 micrograms/L significantly greater than the figure of 29.6 +/- 1.6 micrograms/L in healthy adults in our previous report (P < 0.0001). There was a significant difference in serum levels of PCPB between patients with and without haemodialysis (78.0 +/- 9.4 vs 53.6 +/- 6.3 micrograms/L; P < 0.01). The frequencies of elevated serum levels of procarboxypeptidase B, amylase and lipase greater than upper normal limits were 27.4, 35.7 and 26.2%, respectively. The frequencies of elevated PCPB in patients with and without haemodialysis were 38.2 and 20%, respectively. Only one patient had a serum procarboxypeptidase B level greater than three-fold the upper normal limit. A significant correlation was found between procarboxypeptidase B and lipase (r = 0.785; P < 0.0001). No significant correlation was noted between procarboxypeptidase B vs amylase or renal function tests. In conclusion, in patients with chronic renal failure, the elevation of serum procarboxypeptidase B is as common as the elevations of other pancreatic enzymes.

The sequence and conformation of human pancreatic procarboxypeptidase A2. cDNA cloning, sequence analysis, and three-dimensional model

A full-length cDNA clone coding for human pancreatic preprocarboxypeptidase A2 has been isolated from a lambda gt 11 human pancreatic library. Expression clones were identified by specific interaction with antisera raised against the native protein. The open reading frame of the polynucleotide sequence is 1254 base pairs in length and encodes a protein of 417 amino acids. This cDNA includes a short leader signal peptide of 16 amino acids and a 94-amino acid-long activation segment. The amino acid sequence shows 89% identity to that of rat procarboxypeptidase A2, the only A2 form sequenced so far, and 64% identity to that of human procarboxypeptidase A1. The newly determined sequence was modeled to the three-dimensional crystal structures of both bovine carboxypeptidase A and porcine procarboxypeptidase A1 by a novel distance geometry approach. Biases in the modeling were avoided by relying exclusively on automatic procedures and by using random structures as starting points. Information taken from the known homologous structures refers only to the backbone since no explicit data describing the conformation of side chains were transferred. Ten structures of human carboxypeptidase A2 were determined on the basis of each of the two known crystal structures. The root-mean-square distance for the backbone atoms between the 10 structures and their mean for 237 selected residues is 0.7 A when starting from the bovine protein and 0.8 A for 251 selected residues when starting from the porcine protein. The 94 residue-long activation segment was also determined in the modeling based on the porcine zymogen; its structure is well defined but not its orientation with respect to the enzyme moiety. The model obtained for human procarboxypeptidase A2 is discussed with respect to the specificity and activation of the enzyme.

Molecular cloning of a Drosophila melanogaster gene coding for an homologue of human carboxypeptidase E

PCR primers derived from two functional domains of vertebrate carboxypeptidase E (CPE) were used to generate a probe for screening a size-selected Drosophila melanogaster genomic library. A sequence representing about 50% of the expected complete sequence was obtained by translation of the two open reading frames present on a 1.6 kb DNA genomic fragment. This partial sequence, homologous to human CPE, CPM, and CPN, contained the conserved arginine and zinc binding domains. Similarities to the human enzymes were found with stretches that were equally divergent from the three vertebrate carboxypeptidases. Northern blot analysis revealed the presence of a 6.9 kb transcript for this gene in Drosophila embryos. I postulate that insects possess a single protein fulfilling CPE, CPM, and CPN functions.

Isoforms of procarboxypeptidase B, (pancreas-specific protein, PASP) in human serum, pancreatic tissue and juice

Human Pancreas-Specific Protein (PASP) has been described as a useful serum marker for pancreatic graft rejection and acute pancreatitis. By molecular cloning PASP has recently been identified as procarboxypeptidase B (PCPB). By use of SDS-gel electrophoresis and Western blots, PASP isoforms (proteins interacting with PASP-antiserum) have now been explored in serum and pancreatic tissue and juice. In serum from healthy volunteers, six different isoforms could be visualised. Their MW varied as follows: > 100 K, about 100 K, 45 K, 35-40 K (two bands) about 30 K and 16 K. The 45 K band, corresponding to PASP purified from pancreatic tissue, was always the major band. In pancreatic cytosol and pancreatic juice, the major band corresponded to PASP (45 K) but weak bands were also seen at MW of 40, 30 and 16 K. In serum from 15 patients with acute pancreatitis, PASP was highly increased. Bands corresponding to PASP/PCPB as well as carboxypeptidase B (CPB) were seen simultaneously. During recovery PASP in serum was normalised and the CPB band disappeared. During 12 episodes of pancreatic graft rejection, PASP in serum was also increased but no changes of isoforms in serum were detected. However during these episodes isoforms in pancreatic juice changed dramatically. The band corresponding to PASP disappeared or became much weaker and only bands with lower MW were seen. We have thus observed changes in PASP/PCB serum isoforms during episodes of acute pancreatitis but not at graft rejection episodes although the total increase of PASP in serum was of the same magnitude.(ABSTRACT TRUNCATED AT 250 WORDS)