Molecular mechanisms of apoptosis induced by an immunomodulating peptide on human monocytes

A short immunomodulating peptide (Pa) containing a defined structural motif present in a number of extracellular matrix proteins and autoantigens was found to stimulate human monocytes. Pa-induced apoptosis of isolated monocytes, as indicated by internucleosomal DNA cleavage, increased annexin V binding capacity and cleavage of caspase substrates, such as poly(ADP)ribosylpolymerase. In addition, Bcl-2 protein levels were downregulated during Pa-induced cell death. Nuclear extracts of monocytes incubated with Pa showed higher neutral, Ca(2+)-dependent DNase activity than those obtained from nontreated monocytes. Caspase inhibitors prevented Pa-induced apoptosis, Bcl-2 depletion, and DNase activation. Treatment of monocytes with Pa activated c-Jun N-terminal kinases and p38 kinase, in an acidic sphingomyelinase- and caspase-dependent fashion. Pa-induced apoptosis was blocked by selective inhibitors of p38 kinase (SB203580) and acidic sphingomyelinase (SR33557). These results indicate that JNK and p38 kinase stimulation as well as monocyte apoptosis induced by Pa could depend, at least in part, on early activation of acidic sphingomyelinase.

Immunoregulating properties of peptides related to tumor rejection antigens: effect on human monocytes and natural killer cells

The authors analyzed the effect of several 15-amino acid peptides with sequences related to tumor-rejection antigens, tyrosinase, and the MAGE family on peripheral blood mononuclear cells from healthy donors cultured for periods of 1 to 7 days. Some of these peptides promoted stimulation of monocytes, manifested by phenotypic changes, release of interleukin (IL)-1a, IL-6, and tumor necrosis factor-alpha, and induction of nitric oxide synthase on differentiated CD14++/+ CD16+ DR++ monocytes. An increase in the percentage of cytotoxic monocytes (CD14+/- CD16+) containing granule-associated DNase activity was also observed. Active peptides induced the release of IL-2 and interferon-gamma. Nonspecific natural killer and lymphokine-activated killer cell-mediated cytotoxicity was also observed against classical target cell lines (K-562 and Daudi) and allogenic melanoma cell lines AC and BB, together with an increase in granule-associated DNase in the natural killer cell-enriched population. Monocytes were needed to enhance this innate response, because peptides failed to induce the release of IL-2 on monocyte-depleted peripheral blood mononuclear cells. Data show an enhancement of the rapid innate immune response by peptides related to tumor rejection antigens and suggest that they could also determine the nature of a slow and more definitive specific immune response against tumor cells.

New antiherpetic 1,3-phenylene derivatives, inhibitors of the interaction of the HSV-1 origin binding protein (OBP) with DNA

The synthesis of new 1,3-phenylene derivatives and their preliminary evaluation as antivirals (Herpes simplex 1, HSV-1) whose antiherpetic activity can be related with the inhibition of the interaction of the origin binding protein (OBP) with the DNA are presented. The new compounds are adjusted to a previously defined common structural model, consisting of a central aromatic system, which presents two side chains of different lengths in relative position 1, 3; these chains are made up of atomic groups characterized by the alternation of positive and negative centers, situating differently substituted rings, preferably aromatic, at the ends of both chains. Some of these derivatives, such as N,N''-(4-methoxy-1,3-phenylene)bis[N'-(4-nitrophenyl)urea] (2c) or (1,3-phenylene)bis[N-(p-tolyl)aminosulfonyl] (11b), show antiherpetic activity related to the proposed mechanism.

Kallmann syndrome (hypogonadotropism-anosmia) and Klippel-Feil anomaly in the same patient

A 27-year-old female is described with Kallman syndrome and Klippel-Feil anomaly. This is thought to be the first report of the coexistence of these two conditions in the same patient.

Contribution of phosphodiesterase isoenzymes and cyclic nucleotide efflux to the regulation of cyclic GMP levels in aortic smooth muscle cells

Involvement of phosphodiesterase isoenzymes (PDEs) in guanosine-3',5'-cyclic monophosphate (cGMP) hydrolysis was analyzed in aortic smooth muscle cells. Four families of PDEs were separated from pig aorta: PDE1 (calcium-calmodulin-activated), PDE3 (cGMP-inhibited), PDE4 (adenosine 3',5'-cyclic monophosphate [cAMP]-specific), and PDE5 (cGMP-specific). Within this PDE complement, PDE1 and PDE5 mostly contributed to the hydrolysis of cGMP both in the presence and absence of calcium-calmodulin. The role of these isoenzymes in cGMP degradation was analyzed in primary cultures of porcine aortic smooth muscle cells after stimulation with sodium nitroprusside (SNP) or atrial natriuretic factor (ANF). Pretreatment with 10 microM zaprinast, a concentration that selectively inhibits PDE5, did not potentiate the SNP- or ANF-induced rise of cGMP, questioning the widespread opinion that only PDE5 accounts for cGMP hydrolysis in this tissue. Further evidence came from experiments assessing the effect of zaprinast or 3-isobutyl-1-methylxanthine at concentrations inhibiting both type 1 and type 5 isoenzymes, in which this potentiation was clearly seen. Contribution of cGMP egression to the control of intracellular cGMP levels after SNP or ANF stimulation was also investigated. Shortly after guanylate cyclase activation, extracellular cGMP levels surpassed intracellular levels. However, comparison of the amounts of cGMP extruded to the extracellular medium with those degraded by PDEs leads to the conclusion that efflux is of relatively minor importance in regulating intracellular cGMP levels. In cells made tolerant to SNP, selective PDE5 inhibition synergistically increased intra- and extracellular cGMP amounts after SNP stimulation. These results indicate a previously undescribed greater relevance of PDE5 after tolerance development in aortic smooth muscle cells.

Co-expression of inducible nitric oxide synthase and arginases in different human monocyte subsets. Apoptosis regulated by endogenous NO

Human monocyte subsets, isolated from cultures of mononuclear cells, or freshly obtained from patients with multiple sclerosis, Graves' disease or pemphigus vulgaris, differed in phenotype, apoptotic features, mRNA levels of arginase II (A-II) and the inducible form of nitric oxide synthase (iNOS). Liver-type arginase I mRNA was present in all subsets. Apoptosis was followed by the expression of T cell intracellular antigen (TIA) and the simultaneous detection of DNA stainability by propidium iodine and annexin V binding. Apoptosis was practically absent both in activated CD14(++)CD33(++)DR(++)CD25(++)CD69(++)CD71(++/+) CD16(-) cells, expressing A-II mRNA and having arginase activity, but not iNOS mRNA, and in not fully mature large CD14(++)CD16(+)CD23(+)DR(++) monocytes, expressing simultaneously both mRNAs and having both enzyme activities. However, differentiated small CD14(+/++)CD16(+)CD69(+)CD25(+/-)CD71(++)CD23(+) DR(++) monocytes, expressing high levels of iNOS mRNA, exhibited apoptotic signs. Amounts of NO synthesised by monocytes co-expressing iNOS and arginase changed with the addition of arginine or an iNOS inhibitor; in that case a correlation of NO production and apoptotic features was observed. Data suggest a regulatory role for endogenous NO in apoptosis of stimulated and differentiated monocytes, and also that iNOS and A-II, when simultaneously present, could control the production of NO as a consequence of their competition for arginine.

Spatial and semantic inhibitory processing in schizophrenia

Two experiments assessed inhibitory mechanisms associated with the posterior and anterior attention networks in schizophrenia. Experiment 1 assessed the inhibition of return effect of the posterior network. Both healthy adults and schizophrenic adults showed inhibition of return, suggesting that this inhibitory mechanism of visual orienting is preserved in schizophrenia. Experiment 2 assessed semantic inhibition, which supposedly taps the anterior network, in a lexical-decision task. Healthy adults showed semantic inhibition effects in both visual fields. Schizophrenic adults showed semantic inhibition effects when targets were presented to the left visual field, involving the right hemisphere. However, semantic facilitation rather than inhibition was observed when targets were presented to the right visual field, involving the left hemisphere. These results reflect left hemisphere dysfunction associated with deficits in attentional control in schizophrenia.

Argentine plant extracts active against polymerase and ribonuclease H activities of HIV-1 reverse transcriptase

Lipophilic and hydrophilic extracts of four Argentine plants (Gamochaeta simplicaulis Cabr. 1, Achyrocline flaccida Wein. D. C. 2, Eupatorium buniifolium H. et A. 3, and Phyllanthus sellowianus Muell. Arg. 4) were examined in vitro for their ability to inhibit the polymerase and ribonuclease H (RNase H) activities of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) (wild and Y181C mutant types). The active extracts were also examined as inhibitors of viral replication in HLT4LacZ-1IIIB cell cultures, evaluating their cytotoxicity in parallel. Infusions 2I and 4I, among the crude extracts, showed the highest activity. These extracts were refractioned into four fractions; 2I4 and 4I4 were active as inhibitors of DNA-polymerase (wild and Y181C types) and RNase H activities. These fractions were potent as inhibitors of viral replication and were not cytotoxic. Refractionation of 2I4 yielded five new fractions, two of which, 2I4-4 and 2I4-5, showed notable activity. Refractionation of 4I4 yielded for new fractions; of these, 4I4-3 and 4I4-4 were active. The marked biological activity found in the infusion of A. flaccida and P. sellowianus makes them sufficiently attractive to be considered in the combined chemotherapy of the disease.

Synthesis and anti-HIV-1 activities of new pyrimido[5,4-b]indoles

A set of new pyrimido[5,4-b]indole derivatives that are structurally related to some non-nucleside HIV-1 reverse transcriptase inhibitors were synthesized and biologically evaluated for their activity as inhibitors of wild and mutant HIV-1 RT types in an 'in vitro' recombinant HIV-1 RT screening assay, as well as anti-infectives in HLT4lacZ-1IIIB cells. Preliminary structure-activity relationships suggest that activity is promoted by simultaneous substitution in positions 2 and 4, especially when chains of alkyldiamine type are present, and by electron-releasing substituents (methoxy) in positions 7 and 8. The inactivity or the very low activity of title derivatives does not suggest interest in AIDS therapy.

Spatial and semantic inhibitory processing in schizophrenia

Two experiments assessed inhibitory mechanisms associated with the posterior and anterior attention networks in schizophrenia. Experiment 1 assessed the inhibition of return effect of the posterior network. Both healthy adults and schizophrenic adults showed inhibition of return, suggesting that this inhibitory mechanism of visual orienting is preserved in schizophrenia. Experiment 2 assessed semantic inhibition, which supposedly taps the anterior network, in a lexical-decision task. Healthy adults showed semantic inhibition effects in both visual fields. Schizophrenic adults showed semantic inhibition effects when targets were presented to the left visual field, involving the right hemisphere. However, semantic facilitation rather than inhibition was observed when targets were presented to the right visual field, involving the left hemisphere. These results reflect left hemisphere dysfunction associated with deficits in attentional control in schizophrenia.

The role of nitric oxide in the pathogenesis of multiple sclerosis

Nitric oxide is a free radical gas, NO, of paramount relevance in biology. The enzymes responsible for the synthesis of NO from L-arginine in mammalian tissues are known as nitric oxide synthases (NOS). The inducible NOS (iNOS) is associated with the development of a number of autoimmune diseases. iNOS is induced on monocytes, cells playing a key role in the initiation and progression of the immune response. Induction of the enzyme is effected by proinflammatory cytokines, immunomodulating peptides, and even beta-endorphin through a mechanism involving an increase in cAMP. An excessive production of NO has been implicated in the severe lesions observed in multiple sclerosis (MS). Nitrosation of proteins caused by NO in monocytes may contribute to the formation of new epitopes involved in the autoimmune response. Monocytes/macrophages enhance also their cytotoxic capacity through an increase in NO. iNOS seems to establish a link between neuroendocrine and immune system through beta-endorphin explaining stress-related relapses in MS. One of the causes of demyelination is the lysis of oligodendrocytes by cytotoxic T lymphocytes (CTLs); and T cell response is also known to be modulated by NO.

[Fc gamma receptors in health and disease]

Receptors for the Fc fragment of immunoglobulins G (Fc gamma R) belong to the immunoglobulin superfamily and are expressed on different cell types. These receptors are classified in three different groups (Fc gamma RI, Fc gamma RII and Fc gamma RIII) depending upon their molecular weight, affinity and specificity for their ligands. In addition to all these differences, genetic polymorphisms induce the expression of several isoforms, making the Fc gamma R a heterogeneous group. The Fc gamma Rs have been the subject of intense research on their gene organization, biochemical and structural properties. It has also been established that the Fc gamma R play an important functional role on the regulation of the biological responses that are triggered during inflammatory stages (e.g. an infection), as they link the cellular and humoral branches of the immune response. In this article we give examples of the participation of Fc gamma R on the regulation of the immune response as well as the activation of intracellular mechanisms (transduction signals) after the crosslinking of Fc gamma R by antigen-antibody complexes. The effect of cytokines and growth factors on the regulation of Fc gamma R expression is also described. We discuss the importance of the possible use of some of these molecules to control the expression of Fc gamma R in some clinical situations where alterations on their expression are associated with some diseases. Finally, we analyze the role of Fc gamma R as the point of entry of infectious agents such as HIV.

cAMP activates transcription of the human glucocorticoid receptor gene promoter

Glucocorticoids and cAMP regulate, either in a synergistic or additive fashion, the transcription of multiple genes, although some antagonistic effects of dexamethasone on cAMP-activated transcription have been described. The increased glucocorticoid receptor (GR) mediated response of some cell types, as a result of augmented cAMP, has been considered to be mainly due to an increased stability of GR mRNA, although other plausible explanations should not be ruled out. We studied the possibility that GR transcription itself could be affected by cAMP levels. HeLa cells were transfected with human GR (hGR) promoter constructs and their transcriptional activity determined after inducing a cAMP increase with forskolin. We found that forskolin almost doubled the transcriptional activity of the promoter construct spanning -2995 to +38 of the hGR, whereas no significant variations were observed with shorter chimeras containing sequences downstream -979. Shift mobility showed binding of CREB in vitro to a putative cAMP responsive element located at -1000, suggesting that hGR may be upregulated by cAMP at the transcriptional level, thus adding a new mechanism ascribable to this second messenger, which in conjunction with the cAMP-induced GR mRNA increased stability, would lead to a more precise control of the amount of GR protein within the cell.

Nitric oxide activates granule-associated DNase in human monocytes

Activated and differentiated human monocytes with a CD14+CD16+ phenotype were found to contain a DNase activity associated with secretion granules. Activated cells were obtained from patients with autoimmune diseases. Activation and differentiation of monocytes were also achieved after incubation of PBMC from healthy subjects with protein A (SpA) or immunopotentiating peptides. DNase activity corresponded to a 66-kDa protein, similar to that described in granules from T lymphocytes, active preferentially on double-strand DNA. DNA fragmentation activity increased when NO donors were present; the activity was higher in the presence of Ca2+, and at low pH values. The Ca2+-dependent activity was inhibited by Zn2+. NO-dependent activity was additive with that of Ca2+-dependent and it was not inhibited by Zn2+. Dithiothreitol did not modify the effect of NO on DNase activity. Incubation of PBMC in the presence of NMLA, an inhibitor of NO synthases, decreased this DNase activity. Data reported clearly suggest a regulatory role of NO in granule-associated DNase activity.

Association between dietary fat and breast cancer in Puerto Rican postmenopausal women attending a breast cancer clinic

OBJECTIVE

A pilot case-control study was conducted to examine the possible association between dietary fat intake and the development of postmenopausal breast cancer.

BACKGROUND

Studies regarding the association between dietary fat intake and the development of breast cancer among postmenopausal women are lacking in Puerto Rico.

METHODS

Eighteen cases and eighteen controls were interviewed to obtain sociodemographic information, medical history and dietary fat intake. A semiquantitative food frequency questionnaire containing 67 food items was used to collect the dietary information.

RESULTS

Unadjusted odds ratios (OR) and their 95% confidence intervals (CI) showed a non-significant positive association for total fat intake and the development of postmenopausal breast cancer (OR = 1.57; 95% CI: 0.42-5.90, p = 0.25). The same non significant positive association was found for saturated fat intake (OR = 1.57; 95% CI: 0.42-5.90, p = 0.25). Polyunsaturated fat (OR = 1.25; 95% CI: 0.34-4.64, p = 0.37) and monounsaturated fat (OR = 1.25; 95% CI: 0.34-4.64, p = 0.37) were also positively associated with postmenopausal breast cancer, although the associations were not statistically significant.

CONCLUSIONS

These results are consistent with other case-control studies that have shown non-significant positive associations between total fat and the different components of dietary fat and postmenopausal breast cancer.

Dietary fat and breast cancer: a brief update on current knowledge

Descriptive epidemiologic data suggest a relationship between consumption of high fat diets and breast cancer; although these data can be potentially confounded by other causative exposures. Results of published case-control and cohort studies are inconclusive. Nevertheless, dietary fat significantly affects mammary tumorigenesis in mice and rats in laboratory experiments. We will review current epidemiologic and animal studies, explain the possible mechanisms of how dietary fat may affect breast cancer, and provide preliminary dietary recommendations.

Effective size and polymorphism of linked neutral loci in populations under directional selection

The general theory of the effective size (Ne) for populations under directional selection is extended to cover linkage. Ne is a function of the association between neutral and selected genes generated by finite sampling. This association is reduced by three factors: the recombination rate, the reduction of genetic variance due to drift, and the reduction of genetic variance of the selected genes due to selection. If the genetic size of the genome (L in Morgans) is not extremely small the equation for Ne is [formula, see text] where N is the number of reproductive individuals, C 2 is the genetic variance for fitness scaled by the squared mean fitness, (1 - Z) = Vm/C2 is the rate of reduction of genetic variation per generation and Vm is the mutational input of genetic variation for fitness. The above predictive equation of Ne is valid for the infinitesimal model and for a model of detrimental mutations. The principles of the theory are also applicable to favorable mutation models if there is a continuous flux of advantageous mutations. The predictions are tested by simulation, and the connection with previous results is found and discussed. The reduction of effective size associated with a neutral mutation is progressive over generations until the asymptotic value (the above expression) is reached after a number of generations. The magnitude of the drift process is, therefore, smaller for recent neutral mutations than for old ones. This produces equilibrium values of average heterozygosity and proportion of segregating sites that cannot be formally predicted from the asymptotic Ne, but both parameters can still be predicted by following the drift along the lineage of genes. The spectrum of gene frequencies in a given generation can also be predicted by considering the overlapping of distributions corresponding to mutations that arose in different generations and with different associated effective sizes.

Autosomal dominant inheritance of adducted thumbs and other digital anomalies

Isolated adducted thumbs is an uncommon malformation that occurs sporadically in the majority of cases although some affected families have been reported. Previously, autosomal dominant inheritance was suggested in two familial cases, but this mode of inheritance has not been confirmed. Here we describe a family with adducted thumbs and other digital anomalies in which seven members (six females and one male) are affected in three consecutive generations. Additionally, the patients showed mild abnormalities of fingers 2nd-4th bilaterally and hypoplasia of the middle phalanx of the 5th fingers. This family represents an autosomal dominant condition that apparently has not been previously reported.

Inducible nitric oxide synthase (iNOS) expression in human monocytes triggered by beta-endorphin through an increase in cAMP

Evidence suggesting a relationship between neuroendocrine and immune systems is steadily growing. We demonstrate now that inducible nitric oxide synthase (iNOS) is expressed in human peripheral blood monocytes after incubation of lymphomononuclear cells in the presence of beta-endorphin, a neuropeptide released by the pituitary in response to mental or physical stress or by activated lymphocytes. beta-endorphin raised cAMP level in monocytes. The possible relationship between cAMP and iNOS expression on monocytes was investigated. Immunostaining for iNOS decreased, when besides beta-endorphin an inhibitor of protein kinase A (H-89) was added to the medium at the beginning of the incubation. The cAMP level raised by beta-endorphin was lowered by naloxone, which also reduced slightly iNOS expression. These results clearly point to the monocyte as a link between neuroendocrine and immune systems, an observation of potential relevance in our understanding of how stress and autoimmunity could be interconnected.

Granule associated DNase in T4 and T8 lymphocytes from patients with autoimmune diseases

The presence of a DNase activity associated with secretion granules was detected in T4 and T8 lymphocytes from patients with autoimmune diseases. This activity was much higher in primary biliary cirrhosis (PBC) than in Graves' disease (GD) and multiple sclerosis (MS) or in healthy subjects. This granule associated DNase activity was Ca(2+)-dependent, inhibited by Zn2+, and higher at low pH; its molecular weight corresponded to 66kDa; it was more active with double-strand than single-strand DNA. Judging from its properties this enzyme differed from the three types of endonucleases described as involved in DNA fragmentation (DNase I, DNase II and NUC18). Flow cytometry analysis of T lymphocytes showed that DNase activity associated with CD4+ lymphocyte granules correlated with the ratio CD4+CD45RO+/CD4+CD45RA+ (memory and cytotoxic cells/naive cells, inducers of suppression). In contrast, T8 lymphocyte DNase activity correlated with the proportion of CD4+ lymphocytes with CD4+CD45RA- phenotype (helpers and inducers of cytotoxicity). The possible role of this DNase activity in the mechanisms of lysis or apoptosis mediated by CTL is discussed. We suggest that this DNase activity could be implicated in some of the alterations of the autoimmune response depending on cytotoxic T lymphocytes or T cell inducers of apoptosis.

Analysis of the combined effect of two linear inhibitors on a single enzyme

Different methods for studying the concurrent effects of two linear inhibitors on a single enzyme have been published, including the fractional product of Webb, the Yonetani-Theorell plot or the method of Chou and Talalay. Recently the use of combination plots has also been advocated for this purpose. We have evaluated the applicability of these methods and found that most of them depend on assumptions about the mechanism of action of the inhibitors. If the mechanism of action is not completely understood, or if some assumptions about the mechanism are unfounded, the parameters obtained may be meaningless. Even if these assumptions are correct, the interaction can be advantageously measured using an alternative representation that does not require a knowledge of the inhibition constants and allows experimental data to be retrieved from the plot. In other cases it is the interpretation of the results rather than the validity of the method that is misleading. A common mistake is to take the exclusivity of the effects of two inhibitors as exclusivity of their binding. We show that this assumption is seldom justified. In any case, it is possible to decide whether the combination of two or more inhibitors is more effective than their individual use by means of isobolographic analysis, even when no information about their mechanism of action is available.

Correlation of activated monocytes or B cells with T lymphocyte subsets in patients with Graves' disease

We analyzed the phenotypic characteristics of PBMC from 34 patients with Graves' disease (GD) at different stages of the disease to explore the sequence of immunological events associated with it. In all cases their monocytes were in a state of activation and differentiation more advanced than those of a group of 23 healthy individuals. Strikingly, some patients had CD14++DR- immature monocytes, which were absent in healthy individuals. CD14+CD16+DRhigh monocytes were more abundant in patients. We found a positive correlation between the CD14++DR- monocyte and CD4+CD45RA- helper cells and a negative correlation between the same monocyte subset and CD4+CD45RA+ naive cells. CD14+/++DRlow monocytes directly correlated with this latter T4 subset and CD14+ CD16+DRhigh with CD4+CD45RO+ memory lymphocytes. There was also a positive correlation between memory T4 cells and the subset of activated B lymphocytes (CD19+CD5+) and suppressor T8 cells (CD8+CD11b+). T8 cytotoxic cells (CD8+CD11b-) positively correlated with T4 naive cells. The circulating levels of T3 and TSI (thyroid-stimulating immunoglobulin) directly correlated with a decrease in naive cells and an increase in T8 suppressors. The results suggest that the imbalance suppression/cytotoxicity in GD may be due to a reiterated presentation of autoantigens, or mimetic antigens, to T helpers by mature monocytes and activated B cells.

Correlation between the release of IL-2 and granule-associated DNase activity in human lymphomononuclear cells stimulated with immunomodulating peptides and proteins. Role of different antigen-presenting cells

The authors have already described that a series of short peptides, modelled after sequences related to human extracellular matrix (ECM) proteins and sharing some common structural features, activate Th1 clones through a process involving peptide presentation in HLA-DR proteins. Those peptides induce also LAK- and NK-dependent cytotoxicity as well as activation of monocytes/macrophages present in human peripheral blood mononuclear cell (PBMC) populations. The release of interleukin 2 (IL-2) and interferon gamma (IFN-gamma) by Th cells present in PBMC depleted of macrophages, or B cells is reported, after incubation in the presence of those peptides, fibronectin or Staphylococcus aureus protein A. The authors found that all the molecules tested needed at least the presence of a type of antigen-presenting cell (APC) to exert their stimulatory effect. Some peptides seem to be preferentially presented to Th cells by B cells, while others seem to depend on monocyte/macrophages for this presentation. The dependence on one or another APC seems to be due to differences in the sequences of these peptides. The immunomodulatory agents studied also gave rise to a clear increase in a DNase activity associated with secretion granules of PBMC. That there is a correlation between the release of IL-2 and this DNase activity when using a complete PBMC population, B cell-depleted PBMC or macrophage-depleted PBMC stimulated with the peptides tested has been found.