Alpha interferon gene deletions in post-transplant lymphoma

Post-transplant lymphoproliferative disorder (PTLD) is a well-recognized complication of organ transplant and has been associated with high mortality using conventional chemotherapy. We have investigated 11 cases of PTLD for alterations to the interferon alpha (IFNA) and p16 genes on chromosome 9p using archival material. 4/9 (44%) cases had deletions of the IFNA genes, in contrast to 1/59 (1.7%) cases of intermediate/high-grade de novo NHL drawn from the same geographical region. PTLD may therefore represent a distinct NHL subgroup exhibiting distinct gene pathology.

The earliest T lineage-committed cells depend on IL-7 for Bcl-2 expression and normal cell cycle progression

Interleukin-7 (IL-7)-deficient mice exhibit an early defect in lymphopoiesis. We examined Bcl-2 expression and the cell cycle status of immature thymocyte subsets in these mice. In IL-7-deficient mice, developmental transition to a T cell-committed fate was accompanied by a striking loss of Bcl-2 protein expression and an increased relative proportion of cells in the G0/G1 stage of the cell cycle. Short-term culture of immature thymocytes with rIL-7 caused up-regulation of Bcl-2 protein and cell survival. These data specify a T cell lineage developmental transition point, prior to T cell antigen receptor rearrangement, where IL-7 signal transduction is linked to an anti-apoptosis mechanism and the cell cycle.

Epidemiology and management of open fractures of the lower limb

Epidemiological analysis indicates that 40% of open fractures occur in the lower limb and that the tibial and femoral diaphyses are most commonly affected. Recent advances in fracture stabilization and soft tissue reconstruction technique have improved the outcome of these fractures.

Age-related decreases in chromium levels in 51,665 hair, sweat, and serum samples from 40,872 patients--implications for the prevention of cardiovascular disease and type II diabetes mellitus

This report shows, for the first time using modern analytical techniques, highly significant age-related decreases in chromium levels in 51,665 hair, sweat, and serum samples obtained from 40,872 patients referred by their physicians to an independent medical research clinic and laboratory (r = -.598 to -.762, P < .0001 for all correlations). Males were found to have significantly lower mean chromium levels than females (P < .05 to .0001). There was good correlation between chromium levels in hair, sweat, and serum (r = .536 to .729, P < .0001 for all correlations), indicating that hair and sweat chromium levels are valid additions to the serum levels in assessing chromium status. Chromium measurements in sweat, hair, and serum were performed using graphite furnace atomic absorption spectrophotometry. The influences that age-related decreases in chromium levels might have on increasing the risk to develop age-related impaired glucose metabolism, disordered lipid metabolism, coronary heart disease, arteriosclerosis, and type II diabetes mellitus are outlined, and the role that refined carbohydrates play in the development of compromised chromium status is presented.

Identification of two glycoforms of the MUC5B mucin in human respiratory mucus. Evidence for a cysteine-rich sequence repeated within the molecule

It has been demonstrated previously that respiratory secretions contain three oligomeric, gel-forming mucins; one of these was identified as the product of the MUC5AC gene (1). Here we demonstrate that the other two mucins are glycoforms of the MUC5B gene product. This was accomplished by trypsin treatment of the purified reduced mucin subunit populations and N-terminal sequencing of the liberated peptides. The products of trypsin digestion were separated by gel filtration into high molecular weight mucin glycopeptides and low molecular weight tryptic peptides. The latter were fractionated by reverse phase chromatography, and four of the major peptides were sequenced. Three of these peptides were identical to and contiguous within a 51-amino acid sequence deduced from a cDNA clone (JER57) encoding a portion of the MUC5B mucin. The other peptide is also present within this sequence but showed identity in only 9 of its 10 residues. A polyclonal antiserum raised against one of these peptides was reactive with the two putative MUC5B glycoforms. Analysis of the high molecular weight glycopeptides indicated that the MUC5B subunit contained different types and lengths of glycosylated domains; one domain of Mr 7.3 x 10(5), two domains of Mr 5.2 x 10(5), and a third domain of Mr 2.0 x 10(5). The amino acid composition of the larger two glycopeptides was similar in serine, threonine, and proline content but distinct from that of the smallest glycopeptide. Each of these domains in the mucin subunit is separated by a trypsin-sensitive region, and the relative abundance of the major peptides derived by proteolysis of these regions and their occurrence in a contiguous sequence suggest that they contain a common cysteine-rich motif.

Individual nuclei differ in their sensitivity to the cytoplasmic inducers of DNA synthesis: implications for the origin of cell cycle variability

Nuclei of multinucleate cells generally initiate DNA synthesis simultaneously, suggesting that the timing of DNA synthesis depends upon the appearance of a cytoplasmic signal. In contrast, intact nuclei from quiescent mammalian cells initiate DNA synthesis asynchronously in cell-free extracts of Xenopus eggs, despite the common environment. Here we show that the two nuclei of permeabilized binucleate cells enter DNA synthesis coordinately in egg extracts, as they do in vivo, with different pairs of nuclei initiating replication at different times. This indicates that the two nuclei of a binucleate cell are identical in their sensitivity to the inducers of DNA synthesis in egg extracts; this sensitivity varies in general between the nuclei of unrelated cells. The asynchrony of DNA synthesis shown by unrelated nuclei in egg extracts is therefore not an artifact of the cell-free system but a reflection of genuine differences preexisting within the intact cell. Evidence that these differences between nuclei are responsible for a substantial fraction of G1 variability in living cells is presented.

CFTR-dependent membrane insertion is linked to stimulation of the CFTR chloride conductance

We examined the relation between Cl current (Icl) stimulation and cell membrane capacitance (Cm) when cystic fibrosis transmembrane conductance regulator (CFTR) was expressed in Xenopus oocytes. ICl and Cm increased in parallel when oocytes expressing CFTR were stimulated by forskolin (10 microM) and 3-isobutyl-1-methylxanthine (1 mM). The adenosine 3',5'-cyclic monophosphate (cAMP)-induced increase in surface area detected by Cm was confirmed by morphometry in the same oocytes used for the electrical recordings. These increases in ICl and Cm were reversible and were absent from control oocytes not injected with CFTR cRNA. The time to reach peak ICl lagged slightly behind the peak in Cm. ICl was varied by altering CFTR expression level or agonist dose or by expressing different CFTR mutants. In all cases, there was a close correlation between ICl and Cm, and the kinetics of ICl and Cm stimulation were more rapid the larger the magnitude of the stimulated current. The Cm-ICl relation for wild-type CFTR saturated, consistent with a limited capacity of cells to increase their surface area. These results indicate that stimulation of the CFTR ICl is linked closely to increases in membrane area. This suggests that CFTR is present in the membrane vesicles whose insertion is stimulated by cAMP. The contents of these vesicles may provide a link between activation of CFTR and its cAMP-dependent regulation of other channels.

Differences in friction and torsional resistance in athletic shoe-turf surface interfaces

This study evaluated the shoe-surface interaction of 15 football shoes made by 3 manufacturers in both anterior translation and rotation using a specially designed pneumatic testing system. The shoes included traditional cleated football shoes, "court" shoes (basketball-style shoes), molded-cleat shoes, and turf shoes. Under an 11.35-kg (25-pound) axial load, all shoes were tested on synthetic turf under wet and dry conditions and on natural stadium grass. Test-retest reliability, as calculated using the Pearson Product-Moment Correlation test, was 0.85 for force of translation and 0.55 for the moment of rotation. The wet versus dry surface values on translation were significantly different for rotation about the tibial axis. Spatting, which is protective taping of the ankle and heel applied on the outside of the shoe, resulted in a reduction of forces generated in both translation and rotation. No overall difference between shoes on grass versus AstroTurf was noted. However, there were significant differences for cleated and turf shoes. Shoes tested in conditions for which they were not designed exhibited reproducible excessive or extreme minimal friction characteristics that may have safety implications. On the basis of this study, we urge shoe manufacturers to display suggested indications and playing surface conditions for which their shoes are recommended.

Regression of AIDS-related Kaposi's sarcoma during therapy with thalidomide

A 14-year-old girl with HIV infection and subcutaneous Kaposi's sarcoma (KS) received thalidomide therapy for oral ulcers, resulting in regression of KS lesions, disappearance of KS-associated herpesvirus (KSHV) DNA from blood, and reduced viral load in tumor tissue. Administration of grauntocyte colony-stimulating factor resulted in clinical exacerbation of KS and reappearance of KSHV DNA in blood.

Respiratory mucins: identification of core proteins and glycoforms

At least eight mucin apoproteins are expressed by the tracheobronchial epithelium, but it is not known which, if any, of these are major constituents of the respiratory secretions responsible for the formation of the mucus gel. To address this we have isolated mucins from normal, asthmatic and chronic bronchitic secretions. The asthmatic mucin reduced subunits were fractionated into four populations (I-IV) by anion-exchange HPLC. Amino acid and monosaccharide compositional analysis, as well as M(r) and size measurements, indicate that two of these populations (I and II) are glycoforms of the same or related apoprotein(s) and that the other populations contain two different apoproteins. A panel of antibodies and antisera recognizing the variable number tandem repeat (VNTR) of specific mucin apoproteins did not, as predicted, react with the glycosylated molecules, but after deglycosylation the majority of these probes (with the exception of those to MUC2, which were negative) reacted at a low level with each of the subunit populations. In contrast, an antiserum against a non-VNTR sequence of MUC5AC identified one of the populations (III) as the MUC5AC mucin. The MUC5AC reduced subunit had an M(r) of 2.2 x 10(6) and an RG (radius of gyration) of 57 nm. The genetic identities of the major mucin (populations I and II) and a minor component (population IV) were not established. The MUC5AC mucin was also identified as a major component in the pooled normal secretions from 20 individuals, whereas in a chronic bronchitic sample it was only a minor constituent. Furthermore, in all these different respiratory secretions the MUC5AC mucin appears as a similar biochemical entity, as assessed by Mono Q chromatography and agarose electrophoresis, suggesting that it may have a well-defined pattern of glycosylation in the respiratory tract.

cAMP-regulated trafficking of epitope-tagged CFTR

The cystic fibrosis transmembrane conductance regulator (CFTR) is a phosphorylation-activated chloride channel responsible for cAMP-induced Cl secretion across the apical membranes of epithelial cells. To optimize its detection in membrane localization studies, we tagged CFTR with epitope sequences at the carboxy terminus or in the fourth external loop. The function of six different tagged-CFTRs was tested in two different physiological assays. CFTRs containing the M2 epitope responded to cAMP, whereas cells expressing CFTR with the hemagglutinin HA tag showed little or no cAMP response. Using CFTR tagged in the fourth external loop, we demonstrate that cAMP activation using forskolin results in an increase in CFTR in the plasma membrane of HeLa cells. Forskolin inhibited CFTR endocytosis, and this contributes to the increase in cell surface CFTR expression. Our results indicate that regulation of cell surface CFTR contributes to the increase in plasma membrane Cl conductance evoked by cAMP stimulation.

Biosynthesis of the MUC2 mucin: evidence for a slow assembly of fully glycosylated units

The human colonic cell line PC/AA was grown to near confluency over 24 days and labelled with [14C]proline and [3H]glucose over the last 48 h in culture. The cell layer was extracted with 6 M guanidinium chloride and the mature fully glycosylated mucins were isolated at a density of 1.45 g/ml by using density-gradient centrifugation in CsCl/4 M guanidinium chloride. These mucins were identified as MUC2 with an anti-peptide antibody. The macromolecules were fragmented by reduction into two distinct populations of MUC2 subunits as assessed by agarose electrophoresis. The MUC2 mucin was polydisperse in length, ranging from 500 nm to many microns and its molecular-mass distribution, assessed by rate-zonal centrifugation, ranged from 5 x 10(6) to 40 x 10(6) Da. However, the metabolically labelled MUC2 mucins, though found throughout the whole distribution, were of much smaller average size. Since the entire distribution is not uniformly radiolabelled over 48 h, the formation of the largest species must be preceded by glycosylation and occur slowly, over several days, via the assembly of fully glycosylated units which are likely to be at least dimers [Asker, Baeckstrom, Axelsson, Carlstedt, and Hansson (1995) Biochem. J. 308, 873-880].

Aminoglycoside antibiotics restore CFTR function by overcoming premature stop mutations

Cystic fibrosis (CF) is caused by mutations in the gene encoding the CF transmembrane conductance regulator (CFTR). A single recessive mutation, the deletion of phenylalanine 508 (deltaF508), causes severe CF and resides on 70% of mutant chromosomes. Severe CF is also caused by premature stop mutations, which are found on 5% of CF chromosomes. Here we report that two common, disease-associated stop mutations can be suppressed by treating cells with low doses of the aminoglycoside antibiotic G-418. Aminoglycoside treatment resulted in the expression of full-length CFTR and restored its cyclic AMP-activated chloride channel activity. Another aminoglycoside, gentamicin, also promoted the expression of full-length CFTR. These results suggest that treatment with aminoglycosides may provide a means of restoring CFTR function in patients with this class of mutation.

OCT embedded sections of pathological specimens as a source of high quality RNA for reverse transcriptase/polymerase chain reaction

OCT embedded cryostat sections of stored pathological specimens of non-Hodgkin's lymphoma were used to provide RNA. After reverse transcription to produce cDNA, the polymerase chain reaction was performed with primers for standard and variant forms of the CD44 molecule. Using Southern transfer and hybridisation with a probe specific for exon 4 of the CD44 gene, both standard and variant forms were visualised by autoradiography. This method was shown to be applicable to other gene products by using primers specific for the abl and bcr genes. This technique permits retrospective analysis of RNA from small amounts of stored pathological samples.

Safe at home? Domestic violence and other homicides among women in New Mexico

STUDY OBJECTIVE

To define the contribution of domestic violence (DV) to homicides in women in New Mexico and to examine differences in ethnicity, mechanism, previous documented injuries, incidence of sexual assault, and use of alcohol or illicit drugs between DV- and non-DV-related homicides.

METHODS

We carried out a retrospective analysis of reports of the state office of the medical investigator (OMI) reports from all female homicides from 1990 to 1993 in New Mexico. A homicide was defined as being related to DV if the perpetrator was a current or former male intimate partner. The chi-squared and Mann-Whitney tests were used to analyze data.

RESULTS

The OMI investigated 134 homicides in women for an overall fatality rate of 4.3 per 100,000. A male intimate partner was the perpetrator in 62 cases (46%). The rate of DV homicide among American Indians (4.9 per 100,000) was significantly higher than that among Hispanics (1.7) and non-Hispanic whites (1.8)(RR=2.8; 95% confidence interval (CI), 1.5 to 5.1). Firearms were almost two times as likely to be used in DV homicides as in non-DV homicides (RR=1.8; 95% CI, 1.2 to 2.6). Evidence of old injuries was found more often in DV homicide cases (35.5%) than in non-DV cases (83%) (RR=4.3; 95% CI, 1.8 to 9.8). The presence of alcohol or other drugs was higher among non-DV homicide victims (69%) than DV homicide victims (54.3%) (P=.03).

CONCLUSION

American Indian women are at particularly high risk of homicide, including DV homicide. Firearms were overrepresented in DV homicides, suggesting that removing firearms from the homes of previous DV perpetrators would be a useful public health strategy. Alcohol or illicit drugs were found in approximately two thirds of New Mexico women who were victims of homicide. The high prevalence of history of previous injuries among DV homicide victims indicates that early identification of DV victims in the emergency department and other health care settings is an important point of intervention.

Expression and function of Fas antigen on activated murine B cells

We have studied the expression and function of Fas antigen on murine B lymphocytes. While Fas was present on only a few B cells in the bone marrow, spleen, lymph node or peripheral blood, its expression could be strongly up-regulated by stimulation with soluble CD40 ligand (CD40L). Treatment with anti-IgM and interleukin-4 (IL-4) alone did not induce significant Fas expression but enhanced CD40L-mediated up-regulation of Fas expression. The T cell-derived signal via CD40 is therefore a potent inducer of Fas expression by B lymphocytes. The sensitivity to Fas-mediated apoptosis was found to depend on the duration of B cell activation. B cells activated for 1 day were resistant to Fas-mediated cell death, whereas B cells activated for 3 days were relatively sensitive. Interestingly, different sensitivity to Fas-mediated death signal was observed in 2-day activated B cells. It was found that B cells stimulated with CD40 L alone were more sensitive to Fas-mediated apoptosis than were cells stimulated with CD40L plus anti-IgM or IL-4, and in particular, the combination of the two. The greater sensitivity exhibited by B cells stimulated with CD40L alone seems to be related to limited activation of these cells in the absence of additional stimulation. Co-stimulation of B cells in the presence of CD40L and anti-Fas antibody resulted initially in activation of B lymphocytes, as reflected by the expression of activation markers and cell growth, but this was followed by growth inhibition and cell death. The data demonstrate that the B cell response can be regulated positively and negatively by signaling through CD40 and Fas antigens, respectively.

[Surgical myocardial revascularization during the 1st 15 days of evolution of acute myocardial infarction]

Revascularization significantly improves early and late prognosis in acute myocardial infarction and has prompted substantial changes in therapeutic stategies. We report 140 patients aged 60.3 years old (123 male) operated within 15 days of sustaining an acute myocardial infarction, between January 1984 and December 1989. Coronary angiogram showed single vessel disease in 8 (6%), double vessel disease in 32 (23%), triple vessel disease in 85 (61%) and left main vessel disease in 13 (9%). Indications for surgery were postinfarction angina in 92 patients (66%), multiple severe coronary stenoses in 18 (13%), infarction of less than six hours from onset in 16 (11%), acute angioplasty failure in 7 (5%) and cardiogenic shock in 7 (5%). Thirty one patients were operated during the initial 24 h of infarction (16 with less than 6 h), 14 between the second and third day and 95 between the fourth and fifteenth day. Overall mortality was 4.3% (6/140). Among patients with failed angioplasty and cardiogenic shock, mortality was 23% (7/140), among patients with postinfarction angina this figure was 2.1% (2/92). No patient operated within 6 hours of infarction onset or due to severe coronary stenosis, died. Ninety seven percent of patients were followed during mean of 49 months. Three patients had a new acute myocardial infarction, two had sudden death and two died of unrelated causes. One required angioplasty and none was reoperated. Five years actuarial survival was 95% and the actuarial probability of being free of acute myocardial infarction, angioplasty or reoperation at five years was 99 and 100% respectively. It is concluded that early surgical revascularization in cute myocardial infarction is safe and has excellent long term results.

Analysis of respiratory mucus glycoproteins in asthma: a detailed study from a patient who died in status asthmaticus

Airway mucus from asthmatics is often unusually solid. The death of a patient in status asthmaticus allowed the collection of 28 g of abnormal airway mucus at autopsy. Its chemical and physical properties were studied to reveal differences from more normal airway mucus. The gel plug taken from the airways could be dispersed in 6 M guanidinium chloride, but it took > 1 wk and 700 ml of extractant to disperse 3 g of exudate completely. In contrast, treatment with 10 mM dithiothreitol, which reduces disulfide bonds, dispersed the gel within seconds. Mucins accounted for 25% of the non-dialyzable material in the gel, while DNA constituted < 1% and proteoglycans could not be detected. The mucins were similar in architecture and general composition to other respiratory mucins and were present at a high concentration (approximately 40 mg/ml). The majority of mucins were of extreme size (mean M(r) 30-40 x 10(6)) and slow to dissolve, but sequential extraction experiments on the gel exudate demonstrated a proportion of mucins (15%), the most readily extracted, which had a higher density, 1.45-1.55 g/ml, a lower M(r) (11.5 x 10(6)) and were markedly more acidic than the bulk of the mucins. Both major and minor mucin populations were extremely heterogeneous in mass distribution. Electron microscopy of the major mucin species demonstrated extensive networks of molecules many microns in length. The major mucin species was distinctly less acidic than mucins previously described from either normal or diseased airways. Amino acid analysis of fractions across the charge distribution suggested the presence of at least two different mucin proteins occurring as distinct glycoforms.

Epitope tagging permits cell surface detection of functional CFTR

The cystic fibrosis transmembrane conductance regulator (CFTR) is a phosphorylation-activated Cl channel responsible for adenosine 3',5'-cyclic monophosphate (cAMP)-induced Cl secretion across the apical membranes of epithelial cells. To optimize its detection for membrane localization studies, we tagged CFTR with epitope sequences at the carboxy terminus or in the fourth external loop. When epitopes were added to the fourth external loop, the N-linked glycosylation sites in that loop were either preserved or they were mutated to produce a deglycosylated CFTR (dgCFTR). Tagged CFTRs were expressed in HeLa cells, and their cAMP-sensitive Cl permeability was assayed using the halide-sensitive fluorophore SPQ. CFTRs containing the M2 epitope showed halide permeability responses to cAMP, whereas cells expressing CFTR with the hemagglutinin (HA) tag showed little or no cAMP response. Xenopus oocytes expressing dgCFTR, with or without the M2 epitope, showed Cl conductance responses that were 20% of the wild-type response, whereas M2-tagged constructs retaining the glycosylation sites responded like wild-type CFTR. External M2-tagged CFTR was detected in the surface membrane of nonpermeabilized cells. The surface expression of the mutant M2-tagged CFTRs correlated with processing of these mutants (Gregory et al. Mol. Cell. Biol. 11:3886-3893, 1991). M2-901/CFTR is a useful reporter for the trafficking of wild-type and mutant CFTRs to the cell surface.

[Bacterial translocation in a model of small intestine autotransplant in dogs]

BACKGROUND

Sepsis is the commonest complication of small bowel transplantation. These infections are presumably caused by bacterial translocation, due to splanchnic ischemia.

AIM

To study bacterial translocation in the immediate postoperative period after a small bowel transplantation in dogs and to relate it to splanchnic ischemia.

METHODS

Three groups of dogs were studied. In group A (n = 6) spontaneous episodes of splanchnic ischemia were monitored in the first 18 h of the postoperative period. In group B (n = 5), a 60 min ischemia was induced by superior mesenteric artery occlusion, two hours after small bowel transplantation. In group C (n = 5) a 60 min ischemia was induced by occlusion of mesenteric vein, two hours after transplantation. Bacterial translocation was assessed through bacterial cultures from the mesenteric vein and splanchnic ischemia with intramucosal pH measurement (a pH < 7.2 was considered indicative of ischemia).

RESULTS

Twenty eight of 83 cultures were positive, specially for Gram negative bacilli. The incidence of positive cultures was 14% for group A, 17% for group B and 79% for group C (p < 0.01 compared to groups A and B). The higher incidence of bacterial translocation occurred during the first two hours after transplantation, when the lower intramucosal pH recordings were obtained. The percentage of positive cultures was 39% during periods of ischemia, compared to 24% during periods without ischemia (p = NS).

CONCLUSIONS

Bacterial translocation occurs during the first two hours after intestinal transplantation, in concomitance with the lower intramucosal pH readings.

Murine CD38: an immunoregulatory ectoenzyme

CD38 is an ectoenzyme that utilizes NAD+ and is expressed by many cells of hematopoietic origin. Antibodies to CD38 potentiate many biological activities on lymphocytes, including induction of murine B-cell proliferation. In this article, Frances Lund and colleagues summarize information concerning the expression, enzymatic activity and signal transduction pathway utilized by murine CD38.

A synthetic peptide corresponding to a critical intracellular signaling region of the human IL-4 receptor inhibits IL-4-induced proliferation

We have previously identified a critical region for growth signal transduction in the cytoplasmic domain of the human IL-4 receptor (hIL-4R). Since the entire cytoplasmic domain of this receptor lacks known catalytic activities such as the tyrosine kinase domain, it is likely that the IL-4R associates with other signal-transducing molecules through this critical cytoplasmic region. We test here whether a synthetic peptide corresponding to this critical cytoplasmic region, designated SP-1, interferes with IL-4-induced proliferation by competing with the IL-4R for binding to intracellular signal-transducing molecules. Our data indicated that 100 micrograms/ml SP-1 peptide completely inhibits human IL-4 (hIL-4)-induced proliferation of Ba/F3 transfectants expressing the full-length hIL-4R (hIL-4R-Ba/F3 transfectants). In contrast, a wide concentration range of an unrelated synthetic peptide, designated SP-2, did not affect hIL-4-induced proliferation of hIL-4R-Ba/F3 transfectants. This difference between SP-1 and SP-2 peptides was not due to their differential uptake by cell, since approximately 100 times more SP-2 peptide could be found in cytoplasmic extracts than SP-1 peptide in experiments using radiolabeled peptides. The specificity of SP-1-mediated inhibition of IL-4-induced proliferation was supported by the fact that the SP-1 peptide had no effect on IL-3-induced proliferation of the same hIL-4-Ba/F3 transfectants. In addition, the SP-1 peptide did not affect either IL-2-induced proliferation of Ba/F3 transfectants expressing the human IL-2 receptor beta chain (hIL-2R beta) or hIL-4-induced proliferation of Ba/F3 transfectants expressing a chimeric receptor consisting of the hIL-4R extracellular domain and the hIL-2R beta cytoplasmic domain. SP-1 was unable to inhibit IL-4-induced proliferation of other IL-4-responsive cell lines such as human erythroleukemic cell line TF-1 and mouse T cell lines HT2 and CTLL-2. In addition, SP-1 caused only a 50% inhibition of Ba/F3 cell proliferation induced by mouse IL-4. The failure of SP-1 to inhibit IL-4-induced proliferation in these various cell lines while producing excellent inhibition of hIL-4-induced proliferation of hIL-4R-Ba/F3 transfectants appeared to be related to the number of IL-4Rs expressed on each cell type.(ABSTRACT TRUNCATED AT 400 WORDS)