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At least 19 recordsLinked to original sources
PubMed1991

A comparative study of [Leu1]Tuftsin and tuftsin, a natural phagocytosis-stimulating peptide.

1. [Leu1]tuftsin was reported to have greater phagocytosis-stimulating activity than tuftsin (Thr-Lys-Pro-Arg). 2. However, a study on inactivation of tuftsin by polymorphonuclear leukocytes (PMNs) demonstrated that leucine aminopeptidase, an ecto-enzyme, located on PMN surface was responsible for this mechanism. 3. Since leucine aminopeptidase is known to cleave Leu more easily than Thr at the N-terminal position of peptides, this suggested to us that [Leu1]tuftsin might then be inactivated by PMNs more easily than tuftsin, and thus this analog might be less active than tuftsin. 4. In addition, many tuftsin preparations used in earlier studies were not fully active, as high-performance liquid chromatography was not available to separate out many contaminating diastereomers. 5. In view of this, we have synthesized and purified [Leu1]tuftsin and compared its phagocytosis-stimulating activity with tuftsin. 6. Our results indicate that [Leu1]tuftsin is not as active as tuftsin in stimulating phagocytosis.

Amino Acid Sequence↗
PubMed1987

Tuftsin and tuftsin conjugates potentiate immunogenic processes: effects and possible mechanisms.

The immunoglobulin heavy chain associated tetrapeptide, tuftsin (Thr-Lys-Pro-Arg), known for its phagocytosis-stimulating activity was found to augment the antigen presenting capacity of macrophages in culture when applied simultaneously with the antigen. To study the immunogenic effect of tuftsin in vivo the peptide was coupled covalently to keyhole limpet hemocyanin (KLH) and bovine serum albumin (BSA) antigens to form stable entities. Tuftsin-antigen conjugates were found to be very potent immunogens as tested by their capacity to increase antigen presentation in culture in primary and secondary responses. Thus, monolayers of macrophages pulsed in vitro with KLH-tuftsin conjugates exerted a stronger immunogenic effect than KLH alone. BSA, which by itself was not immunogenic, when applied to macrophages as tuftsin conjugate evoked a high lymphoproliferative immune response. In vivo, BSA conjugated to tuftsin, when injected in aqueous solutions, augmented significantly antibody production, whereas administration of BSA alone or BSA admixed with tuftsin had no immunogenic effect. Studies conducted to elucidate the mechanisms underlying the activation of the immunogenic function of macrophages by the peptide revealed that treatment of cells with antigen and tuftsin increases secretion of interleukin-1 and expression of cell surface Ia encoded antigens. The effect of tuftsin on increasing the immunogenic capacity of antigens may at least partly be attributed to these effects.

Adjuvants, Immunologic↗
PubMed1986

Tuftsin analogues: synthesis, structure-function relationships, and implications for specificity of tuftsin's bioactivity.

Thirteen analogues of the natural macrophage activator peptide tuftsin, ten of which are novel, were synthesized with the aim of exploring the relation between their biological potency and their capacity to attach specifically to cellular tuftsin's receptors. The analogues representing modifications and chain extensions at various parts of the parent tuftsin molecule can be classified as N-terminal analogues, C-terminal analogues, "within-chain" derivatives, or dimers of tuftsin and retrotuftsin. The various synthetic routes employed to prepare the analogues are described. A direct correlation was found between the ability of analogues to inhibit [3H-Arg4]tuftsin specific binding to mice peritoneal macrophages and their capacity to enhance phagocytosis or to inhibit tuftsin-mediated phagocytosis by the cells and to potentiate the cell's immune response.

Animals↗
PubMed1991

Synthesis of glycosylated tuftsins and tuftsin-containing IgG fragment undecapeptide.

Syntheses are described of two new tuftsin derivatives containing a 2-acetamido-2-deoxy-D-galactopyranosyl unit alpha- or beta-glycosidically linked to the threonine's hydroxy side chain function and of the glycosylated undecapeptide corresponding to the tuftsin region of the heavy chain of IgG (amino acid sequence 289-299). The glycosylated tuftsins were synthesized by the solution procedure. Fmoc-[Gal NAc(Ac)3 alpha]Thr-OH and Fmoc-[GalNAc(Ac)3 beta]Thr-OH were allowed to react with H-Lys(Z)-Pro-Arg(NO2)-OBzl by the mixed anhydride procedure and the resulting glycosylated tetrapeptides were fully deblocked by catalytic hydrogenation followed by treatment with potassium cyanide, purified by ion exchange chromatography and characterized by analytical HPLC, elemental and amino acid analyses, optical rotation, and proton NMR spectroscopy. Synthesis of the glycosylated undecapeptide was achieved by the continuous flow solid phase procedure on 4-hydroxymethylphenoxyacetyl-norleucyl derivatized Kieselguhr-supported resin. Fmoc-amino acid symmetrical anhydrides or pentafluorophenyl esters, in the presence of N-hydroxybenzotriazole, were used as the acylating agents. To mimic the native sequence of the tuftsin region at the Fc-domain of immunoglobulin G a 2-acetamido-2-deoxy-beta-D-glucopyranosyl unit was N-glycosidically linked to the amide side chain of Asn 297. The glycosylated asparagine residue was introduced as N2-fluorenylmethyloxycarbonyl-N4-(2-acetamido-3,4,6-tri-O-acetyl-2 -deoxy-beta-D - glucopyranosyl)-asparagine pentafluorophenyl ester. After cleavage from the resin the glycopeptide was deprotected, purified by ion exchange chromatography, and characterized by analytical HPLC, amino acid analysis, high voltage electrophoresis, and proton NMR. The conformational features of the glyco-undecapeptide were determined by circular dichroism measurements both in water and in 98% trifluoroethanol. Results of biological assays will be published elsewhere.

Acylation↗
PubMed1978

Synthesis and biological activity of tuftsin and of [O = C Thr1]-tuftsin. A novel synthetic route to peptides containing N-terminal L -O = C Thr and L - O = C Ser residues.

The cyclization, under alkaline conditions, of N-benzyloxycarbonyl-L-threonine and of N-benzyloxycarbonyl-L-serine to produce 5-methyl-2-oxo-oxazolidine-4-carboxylic acid (O = C Thr1 and 2-oxo-oxazolidine-4-carboxylic acid (O = C Ser), respectively, was investigated and found to be efficient and racemization-free. Similar was the cyclization which accompanied the basic hydrolysis of N-benzyl-oxycarbonyl-L-threonyl-L-phenylalanine methyl ester and of N-benzyloxy-carbonyl-L-seryl-DL-valine ethyl ester, and which resulted in the formation of L - O = C Thr-L-Phe and L - O = C Ser-DL-Val, respectively. The reaction was applied to the synthesis of [O = C Thr1] tuftsin, an active analog of the phagocytosis stimulating peptide tuftsin. A new synthetic route to tuftsin is also described.

Amino Acid Sequence↗
PubMed1977

Tuftsin and some analogs: synthesis and interaction with human polymorphonuclear leukocytes.

The phagocytosis-stimulating tetrapeptide tuftsin, L-threonyl-L-lysyl-L-prolyl-L-arginine, was synthesized by both conventional and polymeric-reagent approaches. Using a combination of the two methods several analogs were prepared, including: [Ala1]tuftsin, [Lys1]tuftsin, [Ser1]tuftsin, [Val1]tuftsin, acetyl-tuftsin, p-aminophenylacetyl-tuftsin and tyrosyl-tuftsin. [Des-Thr1]tuftsin and [omega-NO2(4)]tuftsin were synthesized using a conventional procedure. The effects of synthetic peptides on the phagocytosis of heat-killed yeasts and on the reduction of the dye nitroblue tetrazolium by normal human polymorphonuclear leukocytes were investigated. Tuftsin and to a lesser extent [Lys1]tuftsin and [Ser1]tuftsin were found to stimulate phagocytosis, whereas the other analogs synthesized as well as [Ser1]tuftsin exhibited inhibitory effects to tuftsin's action. Tuftsin alone has stimulated nitroblue tetrazolium reduction; [Des-Thr1]tuftsin and [Ala1]tuftsin repressed this stimulation, while the other peptides showed no effect.

Hexosephosphates↗
PubMed1986

In vivo immunopharmacological properties of tuftsin (Thr-Lys-Pro-Arg) and some analogues.

Tuftsin (Thr-Lys-Pro-Arg) is part of the Fc fragment of a leukophilic IgG and is a stimulator of the phagocytic activity of macrophages and polymorphonuclear cells (PMN) when cleaved from its carrier molecule. Tuftsin was shown to stimulate in vitro all PMN and macrophage functions examined through binding to specific cell surface receptors. In the present work, we provide further evidence that synthetic tuftsin administered to mice may act as an immunomodulator and that its effects on immune functions may result from a primary action on macrophages. After i.v. injection at a dosage of 25 micrograms/mouse, tuftsin stimulated effector (phagocytosis) and regulatory (IL1 production) functions of macrophages and potentiated DTH reaction. Lymphocyte functions (proliferative response to mitogens, T cell-mediated cytotoxicity, IL2 and gamma IFN production) were depressed at times at which macrophage activities were maximally enhanced, suggesting that negative regulatory functions of these latter cells were also stimulated. Tuftsin analogues were synthetized representing substitution or derivatization of the threonyl residue. The relative potencies of these analogues in augmenting phagocytosis-induced chemiluminescence of macrophages were tuftsin greater than or equal to (Gly1)-tuftsin greater than for-tuftsin greater than (for-Met1)-tuftsin greater than (Met1)-tuftsin. Concerning potentiation of DTH reaction the order was (Gly1)-tuftsin greater than or equal to (for-Met1)tuftsin greater than tuftsin greater than (Met1)-tuftsin greater than for-tuftsin. In contrast to tuftsin, none of the analogues induced depression of spleen cell reactivity to mitogens. In addition, (for Met1)-tuftsin administration resulted in an increased production of IL2 and IFN by ConA-stimulated spleen cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1979

Tuftsin-macrophage interaction: specific binding and augmentation of phagocytosis.

The binding of [3H]tuftsin to normal and in vivo stimulated mouse peritoneal macrophage populations was studied at 22 degrees C. The [3H]tuftsin binding to thioglycollate-stimulated macrophages was shown to be rapid and saturable, with an equilibrium dissociation constant (K(D)) (calculated from a Scatchard plot) of 5.3 X 10(-8) M. The calculated number of binding sites per macrophage amounts to approximately 72,000. Binding competition studies with unlabelled tuftsin yielded a K(D) of 5.0 X 10(-8) M. [3H] [N-Acetyl-Thr1]tuftsin, an inactive analog of tuftsin, failed to bind specifically to thioglycollate-stimulated macrophages. [N-Acetyl-Thr1]tuftsin and the tripeptide [Des-Arg4]tuftsin failed to compete for tuftsin binding sites, while [D-Arg4]tuftsin, an analog with small tuftsin-like activity, exhibited a low degree of inhibition of [3H]tuftsin binding. Thus a rather high degree of specificity is involved in the binding of the tetrapeptide. Normal as well as six different macrophage populations induced by stimulation with thioglycollate, concanavalin-A, starch, mineral oil, glucan and Bacillus Calmette Guerrin (BCG), exhibited a similar degree of binding of [3H]tuftsin. Corynebacterium parvum (CP)-stimulated macrophages, on the other hand, showed a 6- to 10-fold-lower capacity for tuftsin binding. Under similar experimental conditions, mouse fibroblast and lymphocyte preparations revealed no detectable specific binding. Tuftsin augmented the phagocytic response of normal and stimulated macrophages assessed both for phagocytosis mediated via the Fc-receptor and via non-specific receptors. CP-stimulated macrophages did not exhibit an increased phagocytic response upon treatment with tuftsin.

Animals↗
PubMed1990

Tuftsin-enhanced thymidine incorporation by murine splenic monocytes.

Tuftsin (Thr-Lys-Pro-Arg), a natural immunomodulating peptide originally found to stimulate phagocytosis by polymorphonuclear leukocytes (PMN), is now known to bind to both PMN and monocyte-macrophages, affecting many of their functions. Administration of tuftsin induces leukocytosis in vivo. We have recently observed that while tuftsin remains in the cytoplasm upon binding and internalization in human PMNs, it translocates into the human monocyte nucleus, suggesting that tuftsin may directly affect growth of monocytes. We have therefore examined the effect of tuftsin on [3H]thymidine incorporation in fractions of murine splenocytes to identify a cell population responding to tuftsin. Tuftsin showed the greatest effect in [3H]thymidine incorporation of splenocytes over controls at optimum conditions of 2% fetal bovine serum and 1 microgram/ml of tuftsin. Splenocyte fractionation by Lymphocyte Separation Medium indicated that tuftsin primarily affects the mononuclear cell fraction; further fractionation revealed that tuftsin affects mostly the monocytes that adhered to plastic. We subsequently further purified the splenic monocytes by repeated plastic adhesion and Percoll gradient separation, to show that tuftsin increases [3H]thymidine incorporation of these highly purified monocytes.

Amino Acid Sequence↗
PubMed1991

The generation of antibody in mice to tuftsin: a naturally occurring phagocytosis stimulating tetrapeptide.

Tuftsin (Thr-Lys-Pro-Arg) is a naturally occurring tetrapeptide that stimulates most known functions of the polymorphonuclear leukocyte and macrophage cell lines. We previously reported our unsuccessful attempts to generate antituftsin antibodies by conjugating tuftsin to several carrier proteins and by polymerizing the peptide with glutaraldehyde. To render tuftsin antigenic the following modifications were made to native tuftsin: three glycine residues were added to the N terminus of tuftsin (Gly3-tuf) and cysteine was added to the N terminus (Cys-tuf) and to the C terminus (tuf-Cys). Native tuftsin was covalently conjugated to sheep red blood cells (SRBC). In a separate experiment Balb/c mice primed with SRBC were immunized with 10(7) SRBC peptide conjugate. Native tuftsin and Gly3-tuf were also conjugated to keyhole limpet hemocyanin (KLH). In another experiment KLH and cationized bovine serum albumin (cBSA) were activated with sulfo-succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (s-SMCC), which was used to control orientation of tuf-Cys and Cys-tuf when conjugated to each carrier protein. All conjugates were administered in complete Freund's adjuvant (CFA) except for cBSA conjugates which were administered in alum. Antibody response was determined by solid phase radioimmunoassay. Results showed that specific antituftsin antibodies were elicited only by Cys-tuf, conjugated to KLH. This study reaffirms that tuftsin is weakly antigenic and confirms the previous work by Gottlieb et al. that antibody to tuftsin can only be elicited when tuftsin is conjugated to the carrier protein KLH in a manner that leaves the peptide carboxyl end free.

Amino Acid Sequence↗
PubMedDate not supplied

The effect of anti-tuftsin antibody on the phagocytosis of bacteria by human neutrophils.

Tuftsin (Thr-Lys-Pro-Arg) is a naturally occurring tetrapeptide which stimulates most known functions of the polymorphonuclear and mononuclear phagocytic cell lines. Although tuftsin is a well characterized bioactive peptide, the exact physiological role tuftsin plays remains unclear. Specific mouse anti-tuftsin antiserum generated in our laboratory, is now available for phagocytosis inhibition studies. Monolayers of human neutrophils were prepared on glass coverslips from a few drops of finger prick blood obtained from a single healthy donor. The monolayers were treated with and without mouse anti-tuftsin antiserum at dilutions of 1:1000 or 1:2000. Exogenous tuftsin (1 microgram/ml) was also added with and without antibody. Treated and untreated neutrophils were subsequently incubated with unopsonized Staphylococcus aureus. The proportion of cells accomplishing phagocytosis (phagocytic index) and the number of bacteria engulfed per cell (avidity index) were recorded. The results showed that exogenous tuftsin increased phagocytosis while the addition of mouse anti-tuftsin antiserum at a 1:1000 dilution inhibited phagocytosis both with and without exogenous tuftsin. This effect was diminished by the antiserum at the 1:2000 dilution. This study reaffirms that tuftsin plays an important physiological role in phagocytosis.

Amino Acid Sequence↗
PubMed1991

Enzyme immunoassay of phagocytosis stimulating tetrapeptide "tuftsin" in normal and leprosy sera.

The serum concentrations of the phagocytosis stimulating the tetrapeptide, tuftsin, were determined by competitive enzyme immunoassay in borderline tuberculoid/tuberculoid (BT/TT, 16 cases), borderline lepromatous/lepromatous (BL/LL, 16 cases), and in healthy controls (20 cases). Using checkerboard titration, 10 ng/well of diphtheria toxoid-p-aminophenylacetyl tuftsin (DTPT) conjugate when incubated with tuftsin antisera at 1:15,000 dilution with a preincubation time of 60 min with the competitor (tuftsin) followed by a further 60-min incubation onto the DTPT-coated wells gave consistent results with a sensitivity of 5 ng/well tuftsin. The mean serum tuftsin concentration was significantly lower in BL/LL patients (134.42 +/- 48.7 ng/ml, p less than 0.01) than in healthy controls (262.86 +/- 59.8 ng/ml), while BT/TT sera (210.94 +/- 75.5 ng/ml) showed slightly decreased levels than did normals, which was not statistically significant. The mean serum IgG levels in BL/LL and BT/TT patients (37.26 +/- 10.99 mg/ml; 28.08 +/- 6.57 mg/ml, respectively) showed significantly (p less than 0.001) higher concentrations than did healthy controls (12.3 +/- 3.6 mg/ml). These observations on the serum concentrations of tuftsin and IgG in leprosy individuals suggest that there is splenic dysfunction in BL/LL patients in terms of the processing of leukokinin to release the free, active molecule tuftsin.

Binding, Competitive↗
PubMedDate not supplied

Potential use of tuftsin in treatment of candida peritonitis in a murine model.

A major complication of continuous ambulatory peritoneal dialysis (CAPD) is peritonitis caused by Candida albicans. Increasing the activity of the peritoneal macrophages, the predominant cell type found in the peritoneal cavity, may be a promising treatment for this infection. Tuftsin was found to increase thioglycollate-elicited mouse peritoneal macrophage activity. 2x10(-7) M tuftsin enhanced two-fold cell association with radiolabelled candida, superoxide aniom production, and killing activity. Thus, a model consisting of mice undergoing peritoneal dialysis was developed in order to study the use of tuftsin as a therapeutic drug against peritoneal candidiasis. Administration of tuftsin (50 micrograms/mouse) before candidiasis induction with a lethal dose of candida (7x10(8) candida per mouse) improved mouse survival up to 70%, compared with 10% in the control group. The potential of tuftsin as a treatment for candidiasis was shown when the infection was induced with a sublethal dose of candida. Daily intraperitoneal injections of tuftsin (50 micrograms) to the sublethally infected mice caused a significant decrease in the number of candida recovered from the peritoneal cavity and from the blood (from 700 +/- 190 to 110 +/- 26 CFU/ml and from 100 +/- 26 CFU/ml to 17 +/- 8 CFU/ml, respectively). In addition, a larger number of peritoneal macrophages with greater phagocytic and killing activity were found in the tuftsin-treated mice. The effect of tuftsin may promote its potential use in the therapy of peritonitis in patients undergoing chronic peritoneal dialysis.

Animals↗
PubMed1990

Effect of tuftsin stimulation on the microbicidal activity exerted by blood monocyte-macrophages of leprosy patients.

The ability of blood monocyte/macrophages from normal donors, tuberculoid leprosy (BT/TT) and lepromatous leprosy (BL/LL) patients to exert enhanced microbicidal activity was assayed after stimulating with 0.8 microM tuftsin, as a function of the duration of cultures in vitro. Normal and BT/TT macrophage cultures showed a statistically significant increase in microbicidal activity against Staphylococcus aureus at all ages of culture (6 h to 14 days), though the overall magnitude of the enhancement shows a decrease with increasing culture age in the same populations. However, 14-day old BL/LL macrophage cultures were unable to undergo tuftsin-mediated stimulation of microbicidal activity against S. aureus and even, fresh 6 h-old cultures exhibited a tuftsin-stimulated response profile similar to 14-day old normal and BT/TT cultures. Also, 7 and 14-day cultures of normal, BT/TT and BL/LL macrophages were unable to inhibit/kill intracellular Mycobacterium leprae after a single stimulation with 0.8 microM tuftsin. However, serial, daily stimulation with 0.8 microM tuftsin resulted in 77-140% inhibition of 3H-thymidine uptake by the 12th day of cultures in vitro in the three groups. These results suggest that BL/LL macrophages exhibit a premature inability to undergo tuftsin stimulated microbicidal activity, which may possibly be reversed by serial dosage of tuftsin.

Blood Bactericidal Activity↗
PubMedDate not supplied

Stability of sterile saline solutions of synthetic tuftsin, a naturally occurring immunomodulating peptide.

Tuftsin, Thr-Lys-Pro-Arg, is a natural immunomodulating peptide originally found as a phagocytosis-stimulating factor for polymorphonuclear leukocytes. The peptide is now known to elicit various other activities including antimicrobial, antiviral and antitumor effects in vivo. Preliminary human studies revealed antitumor and anti-AIDS activities. In view of this clinical potential, we performed studies on the stability of sterile saline solutions of tuftsin stored at 25 degrees C, 5 degrees C, -20 degrees C or -70 degrees C utilizing a phagocytosis assay and analytical HPLC. Tuftsin stored at -20 degrees C or -70 degrees C gradually lost its phagocytosis-stimulating activity; tuftsin stored at 25 degrees C or 5 degrees C lost its phagocytosis activity rather rapidly. By 6 months, tuftsin stored at 25 degrees C lost all activity, and by 12 months, it significantly inhibited phagocytosis. In contrast, HPLC analysis indicated very minor changes. While tuftsin stored at 25 degrees C lost almost all activity by 6 months, we detected appearance of only 1% impurities by HPLC. This study indicates that if its activity is to be preserved, solutions of tuftsin must be frozen for storage.

Adjuvants, Immunologic↗
PubMed1988

Substance P augmentation of CSF-1-stimulated in vitro myelopoiesis. A two-signal progenitor restricted, tuftsin-like effect.

The inflammatory neuropeptide substance P acted as a costimulant for macrophage CSF-1-induced clonal proliferation of murine marrow-derived two signal-dependent mononuclear phagocyte progenitors. Substance P had no effect on clonal proliferation by progenitors responding solely to CSF-1. Substance P fragment 2-11 had no costimulatory activity; however, SP fragment 1-4 retained the full activity of the parent undecapeptide. Fragment 1-4 (ARG-PRO-LYS-PRO), a peptide containing a PRO residue between two positive charges, is a tuftsin-like (THR-LYS-PRO-ARG) tetrapeptide, and tuftsin exerted an identical costimulatory effect. Substance P, SP:1-4, and tuftsin were optimally effective as costimulants at 10(-7) to 10(-6) M. (ALA1)-tuftsin, an inhibitory analog of tuftsin, was a potent negative regulator of two signal-dependent colony formation. (ALA1)-tuftsin at concentrations less than or equal to 10(-9) M exerted dose-dependent inhibition of the positive effects of optimal concentrations of all of the co-stimulants tested, including bacterial LPS. The inhibitory tetrapeptide was equivalent in activity to ferritin, an established inhibitor of two signal-dependent colony formation. The results indicated that SP may influence myelopoiesis in addition to its other inflammatory and immunopotentiating properties. In addition, a potentially valuable modulator of SP and LPS responses in this system, (ALA1)-tuftsin, was identified.

Amino Acid Sequence↗
PubMed1975

The effect of Tuftsin on the nitrous blue tetrazolium reduction of normal human polymorphonuclear leukocytes.

The influence of Tuftsin, the synthetic phagocytosis-stimulating tetrapeptide (L-threonyl-L-lysyl-L-prolyl-L-arginine), on the nitrous blue tetrazolium (NBT) reduction by human polymorphonuclear leukocytes was investigated. It was found that this substance increases the NBT reduction by approximately as much as endotoxin. Other tetrapeptides do not share this property. When Tuftsin analogs are added to the cell suspension and incubated, they prevent the action of both Tuftsin and endotoxin but not of methylene blue. When washed of the analogs, the cells regain the property to be activated by both Tuftsin and endotoxin. It appears that methylene blue on one hand and Tuftsin and endotoxin on the other hand have different sites for their actions. We suggest that whereas methylene blue diffuses into the cell and acts directly upon the hexosemonophosphate shunt activation, Tuftsin and endotoxin appear to act on the cell membrane binding to specific receptors. By treating the cells with Tuftsin analogs, we probably block these receptors.

Arginine↗
PubMed1989

Specific translocation of tuftsin (Thr-Lys-Pro-Arg), a natural immunomodulating peptide, into the nuclei of human monocytes.

To delineate the mechanism of growth and differentiation activities of tuftsin (Thr-Lys-Pro-Arg), we examined the translocation of tuftsin after internalization by the target cells. We found using two independent techniques, fluorescence microscopy and autoradiography, that while in human polymorphonuclear leukocytes (terminally differentiated cells) the peptide remains in the cytoplasmic compartment, in monocytes it translocates to the nucleus. The ability of tuftsin to directly interact with DNA was documented by a large increase in the melting point of bovine DNA in the presence of tuftsin. It is suggested that the translocation, processing and action of tuftsin may depend on the differentiation state and/or on the type of effector cells. Also, tuftsin has the capacity to interact directly with DNA and, therefore, may have a potential for affecting gene activity.

Autoradiography↗