Serum concentrations of aminoterminal propeptide of type III procollagen and propeptide of human type I procollagen in systemic lupus erythematosus

The purpose of this study was to assess the association between the serum levels of aminoterminal propeptide of type III procollagen (PIIINP) and carboxyterminal propeptide of type I procollagen (PICP) with disease activity and damage in systemic lupus erythematosus (SLE). Thirty-three patients with SLE were compared with 31 controls. The assessment in SLE included disease activity indices (SLEDAI, MEX-SLEDAI) and damage index (SLICC/ACR). PIIINP and PICP were measured by radioimmunoassay. Compared with controls, mean levels of PIIINP were higher in SLE (2.9±1.8 vs. 1.8±1.2, P=0.006). PICP was also increased in SLE versus controls (163±94 vs. 102±62, P=0.007). PIIINP was correlated with SLICC/ACR (r=0.33, P=0.048). No correlation was observed between PICP and PIIINP with other clinical or therapeutic variables. These preliminary data suggests a role of PIIINP as a marker for chronic damage. Follow-up studies are required to evaluate its utility in predicting future damage.     

Serum aminoterminal propeptide of type III procollagen after cardiac transplantation and the effect of rejection

The present study examines serum concentrations of the aminoterminal propeptide of type III procollagen (S-PIIINP), a marker of type III collagen synthesis, after heart transplantation, and assesses changes induced by rejection. Fourteen transplant patients were included with 12 coronary artery bypass patients serving as controls. Mild to moderate rejection was found in 44 biopsies, and severe rejection in 6. Two severe rejection incidents occurred before postoperative day 10, the remainder at postoperative days 23 to 57. S-PIIINP was elevated in transplant patients at postoperative days 1 to 7 (p ≤ 0.01), with return to baseline at postoperative day 60 (p = 0.14, N = 6). S-PIIINP remained unchanged after mild to moderate rejection, but increased 1 to 2 weeks following severe rejection occurring after postoperative day 10. S-PIIINP was elevated in bypass patients from postoperative day 2 throughout the study period of 360 days (p ≤ 0.01). Thus, type III collagen turnover after heart transplant and coronary artery bypass grafting resembles wound healing. Collagen synthesis after severe rejection is reflected by SP-IIINP approximately 2 weeks after transplant. The findings may prove to be significant concerning the prognosis of heart transplant patients.     

Hepatic extraction of the aminoterminal propeptide of type III procollagen before and after bile duct ligation in pigs

The aminoterminal propeptide of type III procollagen is extracted from the circulation by the liver, and PIIINP is found in bile. This study was performed in order to investigate whether biliary excretion contributes substantially to the hepatic extraction of circulating PIIINP. Hepatic extraction before and during a 4-h period after ligation of the common bile duct was assessed from serum PIIINP concentrations in a systemic artery, the portal vein and a hepatic vein of seven healthy anaesthetized pigs. Seven sham-operated anaesthetized pigs served as controls. Ligation of the bile duct did not cause a decrease in the hepatic extraction ratio of circulating PIIINP. The PIIINP serum levels of the cholestatic pigs and of the controls were similar throughout the investigation period. The PIIINP concentrations in bile were only 10% of the corresponding serum values. Gel filtration of sera showed that the lower PIIINP concentration in the hepatic vein, as compared to the artery and the portal vein was due to a selective decrease in the concentration of the intact propeptide. The study shows that biliary excretion does not contribute significantly to the hepatic extraction of circulating PIIINP in the normal liver. Furthermore, the hepatic extraction of circulating PIIINP preferentially affects the intact propeptide, rather than the somewhat larger PIIINP related molecule in serum.     

Increased serum procollagen III aminoterminal peptide in myelofibrosis

Myelofibrosis has been shown to involve an increase in type III collagen in the marrow. The aminoterminal procollagen III (PC III) peptide fragment is released during the production of PC III by fibroblasts and its serum level is therefore a marker for type III collagen synthesis. Using a recently developed sensitive radioimmunoassay, serum levels of PC III peptide were measured in 30 patients with myeloproliferative disease and 23 normal volunteers. Levels were found to be elevated above normal values in patients with polycythemia vera, even more elevated in patients with polycythemia and evidence of secondary myelofibrosis with myeloid metaplasia, and most strikingly elevated in patients with agnogenic myeloid metaplasia and severe marrow fibrosis. There was a significant association between serum levels of PC III peptide and the extent of reticulin fibrosis in bone marrow biopsies. Serum PC III level appears to be a quantitative marker for myelofibrosis.     

Is the aminoterminal propeptide of type III procollagen degraded in the liver? A study of type III procollagen peptide in serum during liver transplantation in pigs

The aminoterminal propeptide of type III collagen was monitored in serum during liver transplantation in nine pigs. The aim was to investigate whether removal of the liver causes any changes in the serum concentration of the propeptide. Another connective tissue component, hyaluronan, a glycosaminoglycan known to be degraded in the liver endothelial cells, was also measured. Removal of the liver caused a significant increase in the concentration of the intact propeptide as well as of hyaluronan. Gel filtration confirmed the increase in the amount of intact propeptide. However, another large propeptide-related antigen, eluted near the void volume, appeared in the antigen profile during the anhepatic phase. This peak probably represents the propeptide still attached to the collagen molecule (pN collagen). The findings indicate that the liver is involved in the degradation of the propeptide and of larger propeptide-holding proteins.     

Bone marrow fibrosis and disease activity in multiple myeloma monitored by the aminoterminal propeptide of procollagen III in serum

Simple bone marrow fibrosis is seen in 10–30% of multiple myeloma (MM) patients. We investigated the incidence and characteristics of the bone marrow stromal alterations, in order to characterize the collagens involved by immunohistochemistry, and to evaluate the use of serum aminoterminal propeptide of type III procollagen (PIIINP) as a marker of marrow fibrogenesis and disease activity in MM. 34 consecutive patients with newly diagnosed MM were included prospectively, and followed for 12–30 months. Compared with the findings in 15 normal individuals we found increased interstitial deposits of collagen III in 48% of MM patients, whereas deposits of collagen I were not increased. Interstitial fibrosis appeared to be restricted to areas of severe plasma cell infiltration, but it could also have a more dispersed presentation in the severely infiltrated marrow. There was a high co-distribution of collagen III fibrils and reticulin fibres. Serum PIIINP levels were elevated in most patients, and in the follow-up study serum PIIINP showed a good correlation with the response to treatment. Patients with resistant or progressive disease had continually elevated levels of PIIINP. In most patients with responsive disease serum PIIINP normalized, and we observed no relapses in patients who had normal serum PIIINP levels. Other patients who responded to treatment by reduced M-component level, but had persistently elevated serum levels of PIIINP, had either early relapses or developed progression of osteolytic lesions in spite of unchanged M-component levels. Therefore an elevated serum PIIINP during treatment might indicate an active malignant clone. Serum PIIINP does not simply follow the M-component, but gives further information of potential therapeutic value.     

Independent and additional prognostic value of aminoterminal propeptide of type III procollagen circulating levels in patients with chronic heart failure

BACKGROUND: In chronic heart failure (CHF), changes in the extracellular space contribute to cardiac dysfunction. We aimed to determine whether aminoterminal-propeptide of type III procollagen (PIIINP), a marker of extracellular matrix turnover, might provide prognostic information in CHF patients. METHODS AND RESULTS: A total of 101 consecutive CHF patients (mean age 61.7 +/- 8.7 years, 88% males) were followed up between 1999 and 2001. The combined endpoint of the study was death and hospitalization for heart failure. During follow-up there were 15 deaths and 11 hospitalizations for worsening heart failure. At the survival analysis, age (P = .02), New York Heart Association class (P = .014), s-creatinine (P = .014), plasma-PIIINP (p-PIIINP) levels (P = .005), left ventricular ejection fraction (LVEF) (P = .0002), and a restrictive mitral filling pattern (P = .0003) predicted event-free survival. At the multivariate analysis, p-PIIINP levels predicted outcome independently of other clinical variables, hormones, and echocardiographic and exercise testing variables (P < .05 in all models). In patients with LVEF <31%, the presence of p-PIIINP >4.7 microg/L levels was significantly associated with a higher risk of death and hospitalization as compared with the other patients (event-free survival rate at 12 months: 45% versus 95%; at 24 months: 27% versus 88%; at 36 months: 18% versus 85%, P < .0001). CONCLUSIONS: In patients with CHF, PIIINP levels predict outcome independently of clinical status, hemodynamics and hormonal activation. PIIINP levels provide additional prognostic information to that of left ventricular function alone, suggesting that it may reflect more than cardiac extracellular matrix turnover.     

Synovial fluid and serum concentrations of aminoterminal propeptide of type III procollagen in healthy volunteers and patients with joint disease.

OBJECTIVES--To analyse synovial fluid and serum concentrations of the amino-propeptide of the type III procollagen (PIIINP) in normal individuals and patients with joint disease, and to explore the relationship between synovial fluid PIIINP concentrations and the rheumatological diagnosis, local inflammation, and joint disease. METHODS--A radioimmunoassay was used to measure the PIIINP concentrations in serum and knee joint synovial fluid from 16 healthy volunteers and patients with osteoarthritis (OA) (n = 40), rheumatoid arthritis (RA) (n = 30), and psoriatic arthritis (PsA) (n = 12). The PIIINP measurements were related to demographic data, synovial fluid leucocyte counts, and radiographic changes at the knee. RESULTS--Serum PIIINP concentrations were greater in each of the disease groups than in control subjects, but there were no differences between the disease groups. Synovial fluid concentrations of PIIINP were much greater than those in serum, indicating local production, and were significantly greater in RA than in other disease groups (p < 0.001). There was only a weak positive correlation between synovial fluid leucocyte counts, some radiographic changes, and synovial fluid PIIINP concentrations. CONCLUSIONS--These data suggest that synovial fluid PIIINP concentrations may reflect local synovial proliferative processes in joint disease, and that they could be of diagnostic and prognostic value in inflammatory arthropathies.     

Serum type III procollagen propeptide levels in acromegalic patients

Serum type III procollagen propeptide (PIIIP) is a reliable index of tissue collagen synthesis. Since in acromegaly there is increased collagen production, we measured serum PIIIP in acromegalic patients before any treatment (basal), during medical treatment with the somatostatin analog SMS 201-995, and after pituitary adenomectomy. In all patients, serum GH and plasma somatomedin-C (SmC) levels were also measured. Basal serum PIIIP levels were significantly (P less than 0.01) higher in acromegalic patients (mean +/- SEM, 22.7 +/- 2.1 ng/ml) than in normal subjects (n = 30; 9.7 +/- 0.5 ng/ml), and they were significantly correlated with plasma SmC values (r = 0.31; P less than 0.05). A significant (P less than 0.01) reduction in PIIIP levels occurred in patients treated with SMS 201-995 or surgery (from 24.3 +/- 2.7 to 12.4 +/- 1 ng/ml) as well as in GH and SmC levels. The maximum percent decrease in serum PIIIP was significantly correlated with those in GH (r = 0.65; P less than 0.01) and SmC (r = 0.60; P less than 0.01). Serum PIIIP levels did not change in those patients in whom neither GH nor SmC were decreased by treatment. In conclusion, serum PIIIP levels are elevated in acromegalic patients, and they decline in parallel with GH and SmC during medical or surgical treatment. Serum PIIIP measurements may be useful in the evaluation of acromegalic patients to gain information on the biological activity of GH and in monitoring the course of the disease.     

Serum levels of the aminoterminal propeptide of type III procollagen and hyaluronan during resolving and nonresolving posttransfusion non-A, non-B hepatitis

Serum levels of the aminoterminal propeptide of type III procollagen (PIIINP) and hyaluronan were analysed before and during the acute, recovery and chronic phases of non-A, non-B (NANB) posttransfusion hepatitis (PTH) in 13 patients. All patients were discovered during a prospective study on NANB PTH in patients undergoing open-heart surgery. 7/13 (54%) patients resolved their hepatitis within 6 months after onset, whereas 6/13 (46%) went on to chronic hepatitis. In 5 of these 6 patients a liver biopsy during the chronic phase of the hepatitis showed chronic active hepatitis in 2 and chronic persistent hepatitis in 3. During the acute NANB PTH phase the mean serum PIINP level rose significantly as compared to prehepatitis levels and to levels in a reference group not developing hepatitis. Neither PIIINP levels nor hyaluronan levels, however, could differentiate patients with resolving from patients with nonresolving hepatitis. These markers should, however, be further evaluated as potential markers for development of fibrosis/cirrhosis during chronic hepatitis.     

Long-term monitoring of rec-GH treatment by serial determination of serum aminoterminal propeptide of type III procollagen in children and adults with GH deficiency

Serum aminoterminal propeptide of type III procollagen (PIIINP) levels, a reliable marker of collagen formation, were evaluated in children (C=7) and adults with childhood-onset (CO=10) and acquired (A=18) GH deficiency (GHD) before, during and after withdrawal of rec-GH therapy (C=0.6 IU/kg/week, CO=0.5 IU/kg/week, A=0.25 IU/kg/week). The duration of treatment was 12 months for C and A and 6 months for CO; investigations were carried out before and at 3, 6, 9 and 12 months (for C and A) and at 3 and 6 months (for CO) of GH treatment and 6 months after the withdrawal of therapy (for A and CO). Data obtained from patients were compared with those recorded in two age- and sex-matched control groups. Before treatment, serum PIIINP levels were significantly lower (p<0.001) in C with GHD (mean+/-SE: 2.9+/-0.4 ng/ml) than in controls (6.1+/-0.4 ng/ml), while no significant differences were recorded between adults with CO/A-GHD (3.7+/-0.5 ng/ml and 3.4+/-0.2 ng/ml) and controls (3.2+/-0.2 ng/ml). GH treatment caused a significant increase (p<0.0001) of PIIINP levels both in C (3rd month: 4.4+/-0.2 ng/ml, 6th month: 5.1+/-0.4 ng/ml, 12th month: 5.1+/-0.5 ng/ml), CO-GHD (3rd month: 12.7+/-1.2 ng/ml; 6th month: 10.2+/-0.6 ng/ml) and A-GHD (3rd month: 10.0+/-1.0 ng/ml; 6th month: 8.4+/-0.6 ng/ml; 12th month: 7.0+/-0.7 ng/ml), the increase being dose-dependent (more marked and sustained in adults with CO-GHD). The maximal stimulation of collagen synthesis occurred after 3 months of GH treatment in adults with GHD, while a more gradual and less relevant increase was observed in C with GHD. Six months after the withdrawal of GH therapy, serum PIIINP levels of adults with CO-GHD (3.6+/-0.3 ng/ml) were similar to those recorded before treatment, while in adults with A-GHD serum PIIINP levels (2.6+/-0.2 ng/ml) were significantly lower (p<0.01) than in basal condition. In conclusion, our study shows that: a) GHD is associated with a reduction of soft tissue formation in children, while it seems to exert no relevant effects in adults with GHD; b) GH therapy causes a rapid stimulation of collagen turnover, which shows a different pattern in children and adults; c) the GH-induced stimulation of collagen synthesis is rapidly removed after the withdrawal of GH treatment. For these reasons, the determination of peripheral markers of GH effects appears useful for the monitoring of GH therapy and can contribute to assess the "tailored" substitutive dose for the individual patient.     

Splanchnic and renal extraction of circulating type III procollagen aminoterminal propeptide in patients with normal liver function and in patients with alcoholic cirrhosis

Splanchnic and renal extraction of circulating aminoterminal propeptide of type III procollagen and related antigens were studied in 12 patients with normal liver function and in 19 patients with alcoholic cirrhosis during catheterization. Type III procollagen peptide in serum was measured in two assays: the Type III Procollagen Peptide Radioimmunoassay Kit, a new assay that selectively determines the intact propeptide (and larger type III propeptide-holding antigens) and the Type III procollagen Fab assay that measures both the intact propeptide and the smaller fragments that quantitatively dominate in serum. A significant decrease in the concentration of the intact propeptide between the artery and the hepatic vein was found in the group with normal liver function (p less than 0.01) and in patients with cirrhosis (p less than 0.01). In patients with cirrhosis, however, the splanchnic extraction ratio of the intact propeptide (median = 0.04, range = -0.03 to 0.16) was significantly lower than in patients with normal liver function (median = 0.17, range = 0.05 to 0.36, p less than 0.01). The concentration of the intact propeptide in the hepatic vein was positively correlated to hepatic pressure (n = 18, r = 0.51, p less than 0.05) and inversely correlated to indocyanine green clearance (n = 15, r = -0.61, p less than 0.05). No splanchnic extraction could be demonstrated in the Type III propeptide Fab assay. A significant renal extraction was found in the Fab assay, but not in Type III Procollagen Peptide Radioimmunoassay Kit.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impact of chemotherapy on collagen metabolism: a study of serum PIIINP (aminoterminal propeptide of type III procollagen) in advanced sarcomas

We have previously shown that the serum aminoterminal propeptide of type III procollagen (PIIINP) is a prognostic factor for survival in localised soft-tissue sarcomas, and that elevated values are frequent in metastatic discase. In the present study PIIINP is analysed during chemotherapy in 26 patients with advanced sarcomas. Non-responders had a significantly higher pretreatment level of PIIINP than responders (P=0.05), when only patients with no recent therapeutic interventions were studied. However, during chemotherapy PIIINP followed the clinical course of the malignant disease in only a minority of patients. Patients with recent surgery or recently completed chemotherapy had an increased pretreatment PIIINP value (P=0.03). In these patients PIIINP declined during chemotherapy irrespective of tumour response. A pretreatment PIIINP level within the reference range tended to increase with time irrespective of response. Moreover, the values taken during a chemotherapy infusion were significantly higher than those immediately preceding the corresponding cycle (P=0.001). Our results suggest that pretreatment PIIINP is of value as a prognostic factor for chemotherapy response in patients with advanced sarcomas. During chemotherapy PIINP is of minor importance in monitoring response because of the influence of chemotherapy and other therapeutic interventions on the level of PIIINP.This study was supported in part by grants from the Finnish Cancer Foundations, the Medical Research Council of the Academy of Finland and Finska Läkaresällskapet (Finnish Medical Society)     

Serum aminoterminal type III procollagen peptide in inflammatory and degenerative rheumatic disorders

Summary Measurement of the aminoterminal type III procollagen peptide in serum has been suggested as a marker of the biosynthesis of collagen type III, a major connective tissue component in repair processes. In the present study the propeptide level correlated with the inflammatory synovial mass in rheumatoid arthritis and osteoarthritis. This implies that the propeptide level reflects the collagen type III synthesis occurring in the synovial repair processes, whether they were caused by inflammatory or degenerative rheumatic disorders. Physical activity did not enhance the transition of the propeptide from the synovial fluid or the inflamed synovial membrane to the blood. Normal serum propertide values were observed in most patients with ankylosing spondylitis and degenerative diseases of the spine. This may reflect the lower amount of inflammatory tissue in these diseases and hence the sensitivity of the assays.     

The serum concentrations of the aminoterminal propeptide of procollagen type III and the hepatic content of mRNA for the alpha 1 chain of procollagen type III in carbon tetrachloride-induced rat liver fibrogenesis.

Serum concentrations of the aminoterminal propeptide of procollagen type III (PIIIP) are elevated in fibrogenic diseases of the liver, but the mechanism of elevation is not fully understood. To investigate the mechanism, we compared serum concentrations of PIIIP with total liver content of mRNA for the pro alpha 1 (III) chain, in rats with carbon tetrachloride (CCl4)-induced liver fibrosis. Adult male rats received CCl4 in mineral oil twice weekly for 8 weeks and were compared with age-matched controls. Serum concentrations of PIIIP were measured by a specific radioimmunoassay; molecular sizes of PIIIP in serum were also determined. Pro alpha 1 (III) mRNA content in the liver was quantitated by RNA slot-blot hybridization and chemical measurement of total hepatic RNA content. Total collagen content of the liver was estimated by hydroxyproline measurement. All CCl4-treated animals had septal fibrosis after 4 weeks, and evidence of cirrhosis (regenerative nodules, ascites) was seen after 7 weeks of treatment. Serum concentrations of PIIIP and pro alpha 1 (III) mRNA content in the liver were correlated well until cirrhosis has established. They increased simultaneously after 3 weeks of treatment, 1 week before any elevation of hepatic hydroxyproline could be detected. After cirrhosis has established, pro alpha 1 (III) mRNA content in the liver decreased markedly, but serum PIIIP levels continued to be elevated. Hepatic hydroxyproline plateaued after 5 weeks. The molecular sizes of serum PIIIP indicate the release of intact native procollagen peptide during the development of cirrhosis. In conclusion, at least in CCl4-induced liver fibrosis in the rats, serum PIIIP levels can be used as a fibrogenic marker for the period progressing to cirrhosis. But the use of the serum PIIIP levels in cirrhosis seems to be limited by factors other than liver fibrogenesis.     

Serum concentrations of the carboxyterminal cross-linking domain of procollagen type IV (NC1) and the aminoterminal propeptide of procollagen type III (PIIIP) in chronic liver disease

Serum concentrations of both the carboxyterminal cross-linking domain (NC1) of procollagen type IV and the aminoterminal propeptide of procollagen type III (PIIIP) were measured by specific radioimmunoassays in 60 patients with chronic liver disease and 50 healthy controls. Compared with controls (5.3 +/- 1.3 ng/ml, mean +/- S.D.), NC1 concentrations were significantly elevated in patients with chronic active hepatitis (10.2 +/- 2.0 ng/ml) and liver cirrhosis (13.5 +/- 3.0 ng/ml), but not in chronic persistent hepatitis (6.0 +/- 0.9 ng/ml). The concentrations in patients with active liver cirrhosis were significantly higher than those in patients with inactive cirrhosis. Serum concentrations of PIIIP in controls, parients with chronic persistent hepatitis, chronic active hepatitis and cirrhosis were 5.8 (4.3-7.9), 5.3 (3.5-7.9), 17.5 (10.6-28.9), 16.7 (10.4-26.7) ng/ml, respectively (logarithmic mean and range of mean +/- S.D. after retransformation). Patients with liver cirrhosis had significantly higher concentrations of NC1 in serum than those with chronic active hepatitis, but there was no difference in serum PIIIP concentrations between the two groups. These data suggest an alteration of type IV collagen metabolism in chronic liver disease. In liver cirrhosis, the metabolism of collagen IV is apparently different from that of collagen type III; serum NC1 determinations may therefore provide additional information on chronic liver disease, particularly in patients with cirrhosis with a normal level of serum PIIIP. Further follow-up studies as well as investigations related to the basic mechanism of the elevation of these peptides in serum are needed in order to understand their clinical significance fully.     

Serum hyaluronan and aminoterminal propeptide of type III procollagen in primary biliary cirrhosis: relation to clinical symptoms, liver histopathology and outcome.

Hyaluronan (HA) and aminoterminal propeptide of type III procollagen (PIIINP), two biochemical connective tissue markers, were determined in 76 patients with primary biliary cirrhosis (PBC). The HA and PIIINP concentrations were significantly increased compared with controls (P less than 0.001). Both HA and PIIINP levels correlated significantly with conventional liver-function tests. All patients with stage IV PBC showed increased concentrations of both these variables. However, HA was a better marker with regard to prediction of development of cirrhosis as well as prediction of symptoms. Furthermore, HA also showed a negative correlation with time of survival (P less than 0.05). The present data indicate that HA is a more sensitive marker of liver damage in PBC than PIIINP.     

Aminoterminal propeptide of type III procollagen in serum in alcoholic liver disease

An assay of serum antigens related to the aminoterminal propeptide of type III procollagen has been suggested for monitoring fibrotic processes in the liver. These antigens were measured here in 61 alcoholics who were divided into four groups on the basis of liver histology: normal light microscopy, fatty liver, alcoholic cirrhosis with hepatitis, and inactive cirrhosis. All the subjects having alcoholic hepatitis with cirrhosis had elevated values in the assay, whereas some of those with either fatty liver or inactive cirrhosis still had normal values. It was, therefore, not possible on the basis of this method alone to distinguish fatty liver from cirrhosis or alcoholic hepatitis, although very high values were suggestive of alcoholic hepatitis. In a follow-up study, the aminopropeptide value decreased slowly during recovery from alcoholic hepatitis and increased rapidly after a new drinking bout. The antigens detected by the assay are heterogeneous in human serum. The proportions of the three main peptide forms varied during recovery from alcoholic hepatitis, the authentic propeptide being the main one at the acute stage, but almost disappearing later. The usefulness of the assay could probably be improved if distinct assays were available for the different antigen forms.     

Serum aminoterminal type III procollagen peptide reflects repair after acute myocardial infarction

In 16 patients with acute myocardial infarction and in 15 controls, procollagen type III aminoterminal peptide in serum (PIIINP) was measured consecutively. Serum PIIINP was increased on the second to third postinfarction day (p less than 0.01) and remained elevated for more than 4 months. Peak values were observed on the third to seventh postinfarction day. The individual peak changes were correlated to infarction size calculated from serum CK-MB and serum lactate dehydrogenase (p = 0.60, p = 0.02). The changes in distribution of PIIINP-related antigens in serum after gel chromatography were similar to changes observed during wound healing in humans. PIIINP is cleaved off procollagen type III during the biosynthesis of type III collagen, which characterizes the early stages of repair and inflammation. Our findings suggest that serum PIIINP reflects the repair processes and scar formation following acute myocardial infarction. The serum PIIINP alterations in acute myocardial infarction differ essentially from the changes in myocardial enzymes reflecting myocardial injury. Serum PIIINP may therefore provide new and clinically relevant information on the healing of myocardial infarction.