Internal jugular vein versus external jugular vein anastamosis: implications for successful free tissue transfer.

BACKGROUND: Microvascular free flaps are becoming the reconstructive option of choice for many head and neck defects. Many previous studies have examined factors predicting free flap survival. No study has compared differences in free flap survival when anastomosed to the internal or external jugular systems. METHODS: Retrospective review of all free flaps performed at an academic medical center by a single head and neck microvascular surgeon during the period July 1995 to December 1999. Flaps were closely monitored postoperatively and taken back to the operating room urgently for arterial insufficiency or venous congestion. RESULTS: On hundred fifty-six free flaps were performed during this time period. Sixty-five free flaps were anastomosed to the external jugular (EJ) vein and 86 to the IJ system (62 to the proximal common facial vein, 17 end-side on the IJ, and 7 to other branches). Five had either two venous anastomoses or were anastomosed to other veins and were excluded from statistical analysis. Six (4%) vascular thromboses occurred; 5 were venous and 1 arterial. Success by group was 99% for IJ anastomosis (1 arterial thrombosis) and 92% for EJ anastomosis (5 venous thromboses, p =.03). Urgent anastomotic revision and reperfusion salvaged 5 of the 6 flaps (overall success 99%). CONCLUSIONS: Although the overall success rate (96% success with 99% success with salvage) is comparable to other large series, microvascular free flaps anastomosed to the external jugular vein failed at a significantly higher rate than those anastomosed to the IJ system. This suggests that the IJ system should be used as a recipient vessel when feasible.

Surgical intervention for sinusitis in adults.

This article briefly reviews the latest developments in the indications for and performance of paranasal sinus surgery. Although the central role of medical therapy in the treatment of inflammatory chronic rhinosinusitis remains essentially unchanged, the past few years have seen a gradual evolution in the indications for, and the expectations of, sinus surgery. Although many controversies still exist in the optimal management of rhinosinusitis, especially regarding the treatment of chronic frontal rhinosinusitis, the long-term beneficial role of functional endoscopic sinus techniques in combination with medical therapy has become firmly established for patients who do not respond well to medical treatment alone.

Tumor deposition of laminin-5 and the relationship with perineural invasion.

OBJECTIVES/HYPOTHESIS: Perineural invasion (PNI) is increasingly being recognized as an important indicator of aggressiveness in head and neck squamous cell carcinoma. The mechanisms of PNI are poorly understood. Laminin-5, an important basement membrane constituent, has been shown to be essential in head and neck squamous cell carcinoma invasion and motility. We hypothesized that tumors exhibiting increased expression of laminin-5 are more likely to be neurotropic. STUDY DESIGN: Analysis of archived surgical specimens with and without PNI for presence and intensity of laminin-5 tumor staining. METHODS: Immunohistochemistry of archived head and neck squamous cell carcinoma specimens with known PNI was performed with anti-laminin-5 antibodies and appropriate positive and negative control specimens. The staining patterns were characterized as follows: A, few to no tumor cells positive; B, some peripheral cells positive; C, all peripheral cells positive; and D, almost all tumor cells positive. Statistical analysis was by chi2 analysis. RESULTS: Forty-six PNI-positive and 18 PNI-negative specimens were analyzed. The staining distribution for the PNI-positive specimens was as follows: 2% for A, 41% for B, 46% for C, and 11% for D. For tumors without PNI, the distribution was 28% for A, 50% for B, 22% for C, and 0% for D (P = .005). In PNI-positive tumors, no significant difference in staining was seen between areas with and without PNI. CONCLUSIONS: We found a significant correlation between laminin-5 staining and the presence of PNI in head and neck squamous cell carcinoma. Expression of laminin-5 by tumors is, possibly, an important step in the process of PNI. These preliminary findings support the concept that deposition of basement membrane constituents are required in the multistep process of nerve invasion.

Prevalence of unsuspected acoustic neuroma found by magnetic resonance imaging.

OBJECTIVES: Acoustic neuromas (ANs) comprise 6% of intracranial tumors. Population and autopsy studies have widely divergent estimates of AN incidence. With widespread use of MRI, asymptomatic ANs will be identified, which should improve estimates of the prevalence of this tumor. METHODS: The reports of all brain MRI scans during a 5-year period were retrospectively searched for the diagnosis of AN. MRIs obtained because of a suspicion of AN were discarded, leaving only the unsuspected ANs. RESULTS: A total of 24, 246 MRI studies were performed during this time period. Seventeen patients had unsuspected ANs. Eight tumors were smaller than 1 cm, 6 were between 1 and 2 cm, and 3 were 2 cm or larger. For all MRI scans, we found 7.0 unsuspected ANs per 10,000 brain MRI studies (0. 07%). CONCLUSION: The true prevalence of AN is likely greater than the 10 per million per year previously reported. This implies that there may be a larger number of asymptomatic ANs than previously suspected.

The toxicology of interleukin-12: a review.

Recombinant murine interleukin (IL)-12 (rmIL-12) exhibits antitumor, antiviral, and antimicrobial activities and can modify allergic inflammatory reactions in animal models. Recombinant human IL-12 (rhIL-12) is currently in clinical trials for treatment of cancer, asthma, and viral hepatitis. Principally a phagocyte-derived cytokine, IL-12 targets natural killer cells and T lymphocytes, stimulating their activity and the secretion of interferon (IFN)-gamma. An understanding of the toxicology of IL-12, due in part to effects mediated by IFN-gamma, has emerged from preclinical safety and mechanistic studies and initial clinical trials. Target organs common to several animal species and humans include the lymphohematopoietic system, intestines, liver, and lung.

Comparative immunotoxicity assessment of N4-Trimethoxybenzoyl-5'-deoxy-5- fluorocytidine (Ro 09-1390) and 5'-deoxy-5-fluorouridine (5'-DFUR) in BDF1 mice.

N4-Trimethoxybenzoyl-5'-deoxy-5-fluorocytidine (Ro 09-1390) and 5'-deoxy-5-fluorouridine (5'-DFUR) are 5-fluorouracil (5-FU) derivatives developed as anti-tumor pharmaceuticals. To evaluate immunotoxicities of these compounds, BDF1 mice were administered vehicle, 300-2700 mg (0.68-6.14 mmol)/kg/day of Ro 09-1390, or 100-900 mg (0.41-3.66 mmol)/kg/day of 5'-DFUR for 1 to 7 days, and effects on cellularity in lymphoid organs were assessed by immunohistochemistry as well as general toxicologic parameters. To distinguish compound-specific direct action from nonspecific indirect action caused by dietary reduction, dietary restriction groups were also included as control groups. Final body weight, thymus weight, bone marrow cell number (BMC), and leukocyte number were reduced with high dose of both compounds. Reduction of BMC in groups administered with Ro 09-1390 or 5'-DFUR was more severe than in dietary restriction groups given comparative amount of diet with compound-administered groups. Diffuse thymic cortical hypoplasia was observed in the highest dose of both compounds and more apparent in the Ro 09-1390 than in the 5'-DFUR. Focal nodular thymocyte hyperplasia was observed especially in the lower dose of 5'-DFUR. The results indicate that immunotoxic profiles of Ro 09-1390 and 5'-DFUR are very similar and characterized primarily by myelotoxicity and Ro 09-1390 is approximately two-times less toxic than 5'-DFUR on a molar basis in BDF1 mice.

Role of interferon-gamma in interleukin 12-induced pathology in mice.

Interleukin 12 (IL-12) activates natural killer (NK) and T cells with the secondary synthesis and release of interferon-gamma (IFN-gamma) and other cytokines. IL-12-induced organ alterations are reported for mice and the pathogenetic role of IFN-gamma is investigated by the use of mice deficient in the IFN-gamma receptor (IFN-gamma R-/-). IL-12 caused a rapid infiltration of liver and splenic red pulp with activated macrophages; this and increased NK cells resulted in a fivefold increase of splenic weight in wild-type mice. Splenomegaly was associated with myelosuppression and decreasing peripheral leukocyte counts. IL-12-induced changes in wild-type mice were associated with markedly increased IFN-gamma serum levels and up-regulation of major histocompatibility complex (MHC) class I and II expression in various epithelia. IL-12 induced a qualitatively similar macrophage infiltration in IFN-gamma R-/- mice, less marked splenomegaly (to 2 x normal), and no MHC upregulation. Strikingly increased vascular endothelial intercellular adhesion molecule-1 expression was apparent in both IFN-gamma R-/- and IFN-gamma R+/+ mice. Restricted to mutant mice was a severe, invariably lethal, interstitial, and perivascular pulmonary macrophage infiltration with diffuse pulmonary edema. Extensive quantitative reverse transcriptase polymerase chain reaction analysis revealed an increase of only IL-6 and IL-10 pulmonary gene transcripts in IFN-gamma R-/- mice compared with wild-type mice. IL-12-induced myelosuppression is due to IFN-gamma-release from NK cells and T cells, and is associated with macrophage activation and distinct MHC class I and II antigen upregulation. The pulmonary pathology in IFN-gamma R-/- mice, however, reveals a toxic potential for IL-12 and suggests that endogenous IFN-gamma plays a protective role in preventing fatal pulmonary disease in these mice.

The stimulatory effects of interleukin (IL)-12 on hematopoiesis are antagonized by IL-12-induced interferon gamma in vivo.

Interleukin (IL)-12 synergizes with other cytokines to stimulate the proliferation and differentiation of early hematopoietic progenitors in vitro. However, in vivo administration of IL-12 decreases peripheral blood counts and bone marrow hematopoiesis. Here, we used interferon (IFN) gamma receptor-deficient (IFN gamma R-/-) mice to investigate whether the in vivo inhibition of hematopoiesis by IL-12 is indirectly mediated by IL-12-induced IFN-gamma. IL-12 administered for 4 d (1 microgram/mouse per day) resulted in lower peripheral blood counts and a 2-fold decrease in bone marrow cellularity in wild-type mice, but not in IFN gamma R-/- mice. Bone marrow hematopoietic progenitors were decreased after IL-12 treatment in wild-type mice, but rather increased in IFN gamma R-/- mice. Splenic cellularity was 2.3-fold higher after IL-12 administration in wild-type mice, largely due to natural killer (NK) cell and macrophage infiltration together with some extramedullary hematopoiesis. In IFN gamma R-/- mice, spleen cellularity was less increased, there were fewer infiltrating NK cells, but a strong extramedullary hematopoiesis. Thus, alterations mediated by IL-12-induced IFN-gamma include reduction in bone marrow cellularity and hematopoietic progenitors, as well as pronounced splenomegaly, largely caused by NK cell infiltration. In the absence of IFN-gamma signaling, IL-12 promotes hematopoiesis, consistent with its in vitro activities.

Administration of recombinant interleukin-12 to mice suppresses hematopoiesis in the bone marrow but enhances hematopoiesis in the spleen.

Although IL-12 has been reported to synergize with c-kit ligand (KL) in promoting hematopoietic stem cell proliferation in vitro, administration of recombinant mouse IL-12 (rIL-12) to normal mice caused a dose- and time-dependent anemia, leukopenia, and thrombocytopenia in vivo. Decreased numbers of bone marrow cells were recovered from the tibiae of IL-12-treated mice, and histologic examination of the marrow revealed a loss of mature neutrophils and red blood cell precursors. However, simultaneously with the suppression of hematopoiesis in the bone marrow, the IL-12-treated mice developed splenomegaly, which was largely caused by a marked enhancement of splenic extramedullary hematopoiesis of the erythroid, myeloid, and megakaryocytic lineages. These histologic observations were confirmed by colony-forming cell assays in which administration of IL-12 was shown to cause a time-dependent decrease in bone marrow CFU-GM, CFU-E, and BFU-E hematopoietic colony-forming cells while causing an increase in splenic CFU-GM and BFU-E colony-forming cells. All these effects were reversible upon cessation of IL-12 treatment. The observation that in IL-12-treated mice hematopoiesis was suppressed in the marrow but enhanced in the spleen suggests that myelosuppression was not caused by a direct effect of IL-12 on hematopoietic progenitors. It seems likely that myelosuppression was caused instead by an IL-12-induced alteration in the local environment of the marrow.

Biologic effects of recombinant human interleukin-12 in squirrel monkeys (Sciureus saimiri).

BACKGROUND: Interleukin-12 is a novel heterodimeric cytokine that stimulates the proliferation of activated T and NK cells and induces lymphokine-activated killer cell activity in vitro. To investigate the biological effects of recombinant human IL-12 (rHuIL-12) in vivo, two exploratory studies were conducted in squirrel monkeys (Sciureus saimiri), which have been shown to be pharmacologically responsive to rHuIL-12 in vitro. EXPERIMENTAL DESIGN: In the first study, 18 monkeys (3/sex/group) were given daily subcutaneous injections of 0 (vehicle control), 10, or 50 micrograms/kg/day rHuIL-12 for 14 days. In the second study, 18 monkeys were given 0, 0.1, or 1 micrograms/kg/day rHuIL-12 for 14 days The animals were monitored for clinical signs, hematology and clinical chemistry changes, and sacrificed on day 15 to evaluate gross and histopathologic changes. One monkey in the high dose group was sacrificed moribund on day 14. RESULTS: Monkeys given rHuIL-12 had dose-related hematologic changes characterized by mild to moderate anemia and leukocytosis. Serum chemistry changes included hypoproteinemia, hypoalbuminemia, hypophosphatemia, and hypocalcemia. Gross pathologic findings included generalized lymph node enlargement and splenomegaly with pulmonary edema and peritoneal effusions in two high dose monkeys. Dose-related histopathologic findings included thymic cortical atrophy, splenic lymphoid hyperplasia with histiocytic hyperplasia and extramedullary hematopoiesis of red pulp, Kupffer cell hypertrophy and hyperplasia, trilineage bone marrow hyperplasia, and reactive hyperplasia of lymph nodes. Animals in the 10 and 50 micrograms/kg/day dose groups developed high titers of anti-rHuIL-12 antibodies by day 15. CONCLUSIONS: These studies indicate that rHuIL-12 is bioactive over a wide dose range and induces prominent hyperplasia of hematopoietic and lymphohistiocytic tissues in squirrel monkeys. Moreover, positive immunomodulatory activity (enhanced lymphocyte lytic activity) was detected at a dose of rHuIL-12 that is 500-fold less than the dose causing severe toxicity.

Interleukin-12: a cytokine with therapeutic potential in oncology and infectious diseases.

IL-12 is a cytokine that promotes cell-mediated immunity by promoting Th1-type cytokine responses, enhancing the lytic activity of NK/LAK cells, augmenting specific CTL responses, and inducing the production of IFN-gamma. On the other hand, IL-12 suppresses the development of Th2-type cytokine responses and humoral immunity, particularly IgGl and IgE responses. It is likely that IL-12 normally plays an important role in the host defense against intracellular microbial pathogens. In addition, the administration of rIL-12 to mice has been shown to have potent therapeutic effects in several tumour and infectious disease models. IL-12 has been shown to be more efficacious than IL-2 in several murine tumour models, and toxicology studies suggest that it may have a substantially better therapeutic index. In addition, the long serum half-life of IL-12 relative to other cytokines will allow more flexibility in dosing schedules. However, future clinical trials are required to determine whether the efficacy of IL-12 seen in these experimental models is predictive for its use as an immunomodulatory drug in humans.

Enhanced antitumor efficacy in mice by combination treatment with interleukin-1 alpha and interferon-alpha.

The antitumor efficacy of recombinant murine interleukin-1 alpha (rMuIL-1 alpha) was evaluated either alone or in combination with recombinant human hybrid interferon alpha A/D (IFN-alpha A/D) against the murine B16 F10 malignant melanoma. Treatment of subcutaneous tumor-bearing mice intraperitoneally with rMuIL-1 alpha resulted in a dose-dependent inhibition of tumor growth with the greatest activity obtained with the maximum tolerated dose of rMuIL-1 alpha (10 micrograms per treatment). Augmented tumor inhibition comparable to that seen in mice treated with a high dose of rMuIL-1 alpha was observed in subcutaneous tumor-bearing mice injected with the combination of IFN-alpha A/D and a low dose of rMuIL-1 alpha. Similar inhibition of subcutaneous tumor growth was obtained in T-cell-deficient nude or natural killer cell-deficient beige mice. In contrast, treatment of mice bearing B16F10 experimental pulmonary metastases with rMuIL-1 alpha resulted in no decrease in the number of metastases, and rMuIL-1 alpha did not potentiate the antimetastatic activity of IFN-alpha A/D. A synergistic induction of IL-6 was induced in mice treated with the combination of rMuIL-1 alpha plus IFN-alpha A/D but the level of IL-6 induced was not correlated with inhibition of tumor growth because this elevation of IL-6 was not observed in tumor-bearing nude mice. No direct antiproliferative activity was demonstrable in vitro against B16 F10 cells with rMuIL-1 alpha, IL-6, or rMuIL-1 alpha plus IL-6, and addition of these cytokines did not enhance the antiproliferative activity of IFN-alpha A/D.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration of recombinant IL-12 to normal mice enhances cytolytic lymphocyte activity and induces production of IFN-gamma in vivo.

IL-12 is a heterodimeric cytokine that has been shown to enhance natural killer (NK) and cytotoxic T lymphocyte (CTL) responses, and to induce IFN-gamma production in vitro. In this study, we have examined the effects in vivo of administering purified murine rIL-12 to normal mice. Daily injections of rIL-12 i.p. (1 ng to 10 micrograms/day) caused dose-dependent enhancement of NK cell lytic activity in the spleens and livers of treated mice. Histologic examination of the livers of IL-12-treated mice revealed focal mononuclear cell infiltrates, and flow cytometry studies indicated that the livers of IL-12-treated mice contained increased numbers of NK cells, CD8+ T cells, and monocytes. Liver and splenic lymphoid cells from IL-12-treated mice, unlike liver and splenic lymphoid cells from control mice, spontaneously secreted IFN-gamma in vitro, suggesting that they had been induced by IL-12 to produce IFN-gamma in vivo. Consistent with this, IFN-gamma could be detected in the serum of IL-12-treated mice. In mice which had been immunized by footpad injection of allogeneic splenocytes, daily administration of rIL-12 i.p. was shown to enhance the specific CTL response in the draining lymph nodes. Thus, these studies demonstrate that IL-12 can enhance NK and CTL activity and induce IFN-gamma production in vivo, as well as in vitro, and suggest possible mechanisms by which IL-12 may exert therapeutic effects in the treatment of some tumors and infectious diseases.

Cytokine-induced changes in the leukon.

Cytokines are regulatory peptides, produced by virtually every nucleated cell type in the body, that have pleiotropic effects on hematopoietic, lymphoid, and other cell types. Cytokines usually act locally as autocrine or paracrine cellular signals intended to maintain local homeostasis but in disease states can spill over into the circulation to initiate systemic reactions. The systemic administration of high doses of recombinant cytokines is associated with a multitude of pharmacologic and toxicologic effects, frequently involving the hemolymphopoietic system. These effects may represent direct or indirect pharmacologic or hyperpharmacologic activity or may represent toxicity. The objective of this review is to present the general types of hemolymphopoietic changes associated with cytokine administration to animals and to provide examples of cytokine-induced effects on the hemolymphopoietic system.

Peripheral neuropathy induced by 2',3'-dideoxycytidine. A rabbit model of 2',3'-dideoxycytidine neurotoxicity.

The nucleoside analog 2',3'-dideoxycytidine (ddC) is a potent inhibitor of the reverse transcriptase of human immunodeficiency virus and a DNA chain terminator. In clinical trials in patients with acquired immunodeficiency syndrome, ddC treatment has been associated with a dose-limiting and dose-dependent, painful, sensorimotor peripheral neuropathy. In search of an animal model for ddC-induced neurotoxicity we studied 36 New Zealand White rabbits (3 males/3 females/group) given 0, 10, 50, 100, 150, or 250 mg/kg/day of ddC, by oral intubation, for 13 or 18 weeks. Rabbits in the 150 and 250 mg/kg/day groups were sacrificed at 13 weeks because of hematopoietic toxicity. After 16 weeks, rabbits in the 50 and 100 mg/kg/day groups showed hindlimb paresis and/or gait abnormalities. Nerve conduction velocities and amplitudes in the 100 mg/kg/day rabbits were reduced by 30 to 50%. The most prominent pathologic changes in peripheral nerve and ventral roots of ddC-treated rabbits were (a) myelin splitting and intramyelinic edema, (b) demyelination and remyelination of axons, and (c) axonal loss. Treatment-related histologic lesions were not observed in spinal cord, brain, or retina. The pathology in these ddC-treated rabbits is consistent with a peripheral myelinopathy and axonopathy. This represents the first clinical, electrophysiologic, and pathologic description of an animal model of a peripheral neuropathy induced by a nucleoside analog.

Hematological effects of 2',3'-dideoxycytidine in rabbits.

The antiviral nucleoside analogue 2',3'-dideoxycytidine (ddC) is a DNA chain terminator and/or inhibitor of human immunodeficiency virus (HIV) reverse transcriptase. We evaluated the effects of ddC in 36 New Zealand white rabbits. Three/sex were assigned to a control group and 5 treatment groups (10-250 mg/kg/day) for 13 or 18 weeks. Blood samples were taken 1 week prior to treatment and weekly thereafter to termination with the exception of the 2 highest dose groups, where blood sample collection was terminated at week 13. Selected hematological analytes were measured weekly with the exception of prothrombin time (PT) and activated partial thromboplastin time (APTT). PT and APTT and selected biochemical analytes were measured prior to treatment, at 7 weeks, and after 13 weeks of treatment. All rabbits were necropsied. Giemsa and hematoxylin and eosin sections were prepared from methacrylate-embedded marrow. Hematological effects included decreases in red blood cell count, hemoglobin, hematocrit, and white blood cell count and increases in mean corpuscular volume and red cell distribution width. Platelets, platelet volume, PT, APTT, and mean corpuscular hemoglobin concentration values were variable or unchanged. Effects were dose-related, most were seen at 1 week, and they persisted to term. Bone marrow histopathologic changes included megalocytosis, erythroid hypoplasia, bizarre erythroid nuclear morphology, nuclear-cytoplasmic asynchrony, and increased mitotic figures. Lymphopenia caused by ddC plateaued at 2 weeks and persisted until termination. Heteropenia (neutropenia) was sporadic. Biochemical values for serum analytes were unchanged by treatment. The principal hematological effect of ddC upon the erythron was characterized as a nonregenerative macrocytic anemia with erythroid hypoplasia and megaloblastic erythropoiesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison between effects of interleukin-1 alpha administration and sublethal endotoxemia in primates.

Interleukin (IL)-1 is an early mediator of host response to inflammation, although its contribution to individual components of the acute phase reaction is still unclear. To evaluate how the hemodynamic, metabolic, and hormonal responses to sublethal endotoxemia compare with IL-1 administration, baboons received intravenously either lipopolysaccharide (LPS) or 0.1, 10, or 100 micrograms/kg IL-1 alpha. LPS induced an early tachycardia and a fall in mean arterial pressure, as well as lacticacidemia and hypoaminoacidemia. Similar hemodynamic and metabolic changes were seen with 10 or 100 micrograms/kg of IL-1 alpha. An increase in adrenocorticotropic hormone and fall in serum iron were induced by IL-1 alpha but not by LPS. Plasma tumor necrosis factor-alpha (TNF-alpha) was not measurable after IL-1 alpha administration, whereas LPS induced a monophasic TNF-alpha response. IL-6 levels were significantly greater after LPS than IL-1 alpha administration. Histopathological lesions, similar in LPS- and 100 micrograms/kg IL-1 alpha-treated groups, were present only in the adrenal cortex. We conclude that many, but not all, of the effects of sublethal endotoxemia can be replicated by IL-1 alpha administration, and these responses are dose dependent.

Differential release of active proteinase inhibitors by two rat mammary adenocarcinoma variants possessing different metastatic potentials.

The ability of tumor cells to express elevated levels of proteinases capable of degrading tissue matrix and basement membrane components in vitro has been correlated to their invasive and metastatic potential. Many in vitro invasion assays have been performed either in the presence of serum or with tumor cells that had been previously grown in serum. Since serum contains large amounts of active proteinase inhibitors, their presence could complicate interpretations. We have, therefore, attempted to measure the amounts of serine proteinase inhibitors released into culture medium by two rat mammary adenocarcinoma metastatic variants selected in vitro for serum-independent growth and differing in their in vivo metastatic behavior. Concentrated spent media (CSM) derived from cultures of poorly metastatic MTLn2(T42D) and highly metastatic MTLn3(T17D) tumor cells, grown in the presence and absence of fetal bovine serum (FBS) for 20-24 h, were compared for the presence of serine proteinase inhibitors capable of inactivating alpha-chymotrypsin. Our results show that when MTLn2(T42D) and MTLn3(T17D) tumor cells were exposed to FBS, the CSM of MTLn2(T42D) exhibited nearly 5-fold greater amounts of active proteinase inhibitors than that of MTLn3(T17D). The amount of proteinase inhibitory activity detected in the CSM of tumor cells not exposed to FBS was not eliminated but declined by 82% and 37% for MTLn2(T42D) and MTLn3(T17D), respectively. Analysis for enzyme-inhibitor (E-I) complex formation by nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography confirmed the kinetic results and revealed that the major inhibitor present in CSM/FBS of both variants forms a heat- and sodium dodecyl sulfate-stable E-I complex with an apparent molecular weight of approximately 79,000, identical to that formed when FBS or purified alpha 1-proteinase inhibitor is incubated with [alpha-125I]chymotrypsin. E-I complexes with apparent molecular weights of 44,000 and 50,000 were formed from CSM/bovine serum albumin of MTLn3(T17D) and MTLn2(T42D), respectively, that were not detected when [alpha-125I]chymotrypsin was incubated with bovine serum albumin. We infer from these observations that, in culture, poorly metastatic MTLn2(T42D) tumor cells, as compared to their highly metastatic MTLn3(T17D) counterparts, exhibit an increased capacity to retain and subsequently release significantly greater amounts of serum-derived active proteinase inhibitors. Moreover, the detection of proteinase activity by kinetic analysis and E-I complexes by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography in CSM prepared from cultures not exposed to FBS indicates that both variants have the capacity to produce their own inhibitors.(ABSTRACT TRUNCATED AT 400 WORDS)