Oviposition dynamics of Aedes aegypti in Central Argentina

Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) is the vector of multiple arboviruses. To evaluate the association between environmental factors and the oviposition activity of Ae. aegypti in Argentina, data on the presence and abundance of eggs were collected using ovitraps, between September of 2018 and May of 2019, in the cities of Villa María, Río Cuarto and Salsipuedes (Córdoba province, Argentina). We analysed the relationships between oviposition and five environmental factors: Temperature, precipitation, vegetation cover, human population density and distance to sites with a potential high density of larval habitats, like cemeteries and trash dumps. Environmental factors' data were collected using satellite image products. The oviposition activity was randomly distributed in three cities. Using generalized linear mixed models, we show that the house where each ovitrap was placed was a source of variability in oviposition, suggesting the relevance of microsite factors and the importance of domestic control actions. Ae. aegypti oviposition was positively correlated with night-time temperature of the previous 3 weeks, and in a context-dependent manner, it was positively correlated with human population density, vegetation cover and precipitation. The consistency and magnitude of these relationships varied between cities, indicating that oviposition is related to a complex system of environmental variables.

Oxidized LDL/β2-glycoprotein I complexes: new aspects in atherosclerosis

β2-glycoprotein I (β2GPI) is a major antigenic target for antiphospholipid antibodies. Oxidized low-density lipoprotein (oxLDL) is the principal lipoprotein found in atherosclerotic lesions, and it colocalizes with β2GPI and immunoreactive lymphocytes. oxLDL/β2GPI complexes appeared in the blood circulation of patients with diseases, such as systemic lupus erythematosus (SLE), antiphospholipid syndrome (APS), systemic sclerosis, diabetes mellitus and chronic renal diseases. Thus, the complexes may be associated with systemic and chronic inflammation of the vasculature. IgG anti-oxLDL/β2GPI complexes autoantibodies and their immune complexes were detected only in SLE/APS patients and in its animal model and were strongly associated with arterial thrombosis. The oxLDL/β2GPI complexes were internalized by macrophages via IgG anti-β2GPI antibody-mediated phagocytosis. In contrast, IgM anti-oxLDL antibodies derived from hyperlipidemic mice reduced the incidence of atherosclerosis. The distribution patterns of IgG and IgM anti-oxLDL antibodies in patients suggest the different roles of these antibodies.

Oxidized low-density lipoprotein and β2-glycoprotein I in patients with systemic lupus erythematosus and increased carotid intima-media thickness: implications in autoimmune-mediated atherosclerosis

Oxidative stress and LDL modification (oxLDL) are early pro-atherogenic events. OxLDL binds β2GPI producing immunogenic oxLDL/β2GPI complexes. Antibodies to these complexes have been associated with arterial thrombosis in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). Circulating oxLDL/β2GPI complexes, IgG and IgM antibodies to these complexes were measured by ELISA in 30 SLE patients asymptomatic for cardiovascular disease (mean age 31 years) and 27 age/sex matched healthy controls. Carotid intima-media thickness (IMT) was measured by ultrasound in all patients and controls. Forty-seven percent of SLE presented plaques (median IMT of 0.65 ± 0.12 mm) while only 7% of the controls had plaques (median IMT of 0.50 ± 0.04 mm, P < 0.001). Median optical density (OD450nm) for oxLDL/β2GPI complexes in SLE was 0.244 ± 0.07, higher than controls (0.174 ± 0.09, P < 0.001). Median OD for IgG anti-oxLDL/β2GPI antibodies was also higher in SLE (0.297 ± 0.26) compared to controls (0.194 ± 0.07, P < 0.001) while the median OD for IgM antibodies in SLE (0.444 ± 0.46) was not different than controls (0.326 ± 0.22, P = 0.267). There was no correlation between IMT and oxLDL/β2GPI complexes, IgG or IgM antibodies, possibly reflecting the complex interrelationship between these serologic elements and tissue factors in the arterial wall. These results support the hypothesis that oxLDL/β2GPI complexes and IgG (not IgM) anti-oxLDL/β2GPI antibodies contribute to the development of autoimmune-mediated atherosclerosis

Atherogenic Oxidized Low-Density Lipoprotein/β2-Glycoprotein I (oxLDL/β2GPI) Complexes in Patients with Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Oxidized low-density lipoprotein (oxLDL) interacts in vitro with β2-glycoprotein I ( β2GPI) via LDL-derived specific ligands forming oxLDL/ β2GPI complexes. Circulating oxLDL/ β2GPI complexes have been demonstrated in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). Autoimmune vascular inflammation and oxidative stress contribute to oxLDL/ β2GPI complex formation. Immunohistochemical staining of atherosclerotic lesions suggest that these complexes are formed in the arterial wall and released into circulation. The demonstration of antibodies to oxLDL/ β2GPI complexes indicates that these complexes are immunogenic, and the coexistence of complexes and antibodies suggest an active pro-thrombotic/pro-atherogenic role in the development of autoimmune vascular complications. Circulating oxLDL/ β2GPI complexes can be measured by ELISA using a monoclonal antibody specific to complexed human β2GPI to capture β2GPI bound to oxLDL. An enzyme-conjugated monoclonal antibody to human Apo B 100 allows the specific detection of oxLDL/ β2GPI complexes. OxLDL/ β2GPI complexes were common in SLE and APS patients suggesting an underlying process of inflammation and oxidation. Using oxLDL/ β2GPI complexes as capture antigen, antibodies to oxLDL/ β2GPI can be measured by ELISA. Serum levels of IgG anti-oxLDL/ β2GPI antibodies were significantly higher in SLE patients with APS compared to SLE controls without APS. Further, high titers of these IgG antibodies were observed in APS patients with a history of arterial thrombosis. The presence of circulating oxLDL/ β2GPI complexes and IgG antibodies to these complexes indicates significant vascular injury and oxidative stress as well as an active role in autoimmune-mediated atherothrombosis.

The smart life

The Smart Life is an approach conceptualized from a frame of prevention, focused on youth, and aimed toward fostering independent and productive life styles. Currently, the focal concern is on African American youths, ages 12 through 18, who reside in rural areas of North Central Florida. Implemented through seminars, the Smart Life approach is grounded in theory and practice. It is built on grass roots efforts directed toward enlightening youths about the ways to improve their future through formulating goal-directed plans, and awakening their abilities to realize healthy and productive lives. The theoretical framework encompasses both Erik Erikson's psychoanalytic theory of identity development and the life cycle, as it accentuates the psychosocial nature of identify formation during adolescence, and Albert Bandura's social learning theoretical formulations specific to self-efficacy in terms of perceived self-competence.The seminars, held in various community-based settings, cover several areas. The issue to identity is always addressed. Discussions include: the meaning of being an African American, information on the history and global locations of people of African descent, and encouragement to make attachments. The other 4 critical areas that The Smart Life seminars focus on include the prevention of: crime and violence, early sexual experiences and pregnancy, alcohol and drug use and abuse, and school failure.

Pathophysiology of β2-glycoprotein I in antiphospholipid syndrome

Since β2-glycoprotein I (β2GPI) was described as the major antigenic target for antiphospholipid antibodies, many studies have focused their attention to the physiological role of β2GPI and anti-β2GPI antibodies on autoimmune-mediated thrombosis. Studies reporting the physiological role of β2GPI have been numerous, but the exact mechanism of action(s) has yet to be completely determined. β2GPI’s epitopes for anti-β2GPI autoantibodies have been characterized, however, not all of the heterogeneous anti-β2GPI antibodies are pathogenic. The pathophysiologic role of β2GPI has been reported in the fields of coagulation, fibrinolysis, angiogenesis, and atherosclerosis. Our understanding of the impact of β2GPI, its metabolites and autoantibodies to β2GPI on these physiological functions may contribute to the development of better therapeutic strategies to treat and prevent autoimmune-mediated atherothrombotic vascular disease. Lupus (2010) 19, 379—384.

Autoimmune-mediated atherothrombosis

Autoimmune vascular inflammation and oxidative stress (lipid peroxidation) are common in systemic autoimmune diseases and contribute to the oxidative modification of low-density lipoprotein (oxLDL) and oxLDL/beta2GPI complex formation. Circulating oxLDL/beta2GPI complexes have been detected in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). The presence of antibodies to oxLDL/beta2GPI complexes indicates that these complexes are immunogenic, and the coexistence of complexes and antibodies has pointed to an active proatherogenic role in the development of autoimmune vascular complications. Immunohistochemical staining of atherosclerotic lesions suggest that these complexes are formed in the arterial wall and released into circulation. The in vitro macrophage uptake of oxLDL/beta2GPI complexes was significantly increased in the presence of antiphospholipid antibodies, either beta2GPI-dependent anticardiolipin or anti-beta2GPI antibodies, suggesting that macrophage Fcgamma receptors are involved in lipid intracellular influx and foam cell formation. These findings provide an explanation for the accelerated development of atherosclerosis seen in SLE and APS. The presence of circulating oxLDL/beta2GPI complexes and IgG antibodies to these complexes indicate significant vascular injury and oxidative stress as well as an active role in autoimmune-mediated atherothrombosis.

Autoimmune diseases and infections: controversial issues

The etiology and pathogenesis of certain types of disease remain controversial and stand like a bridge that crosses infectious, autoimmune and autoinflammatory pathways. Infection, for example, may initiate a disease, although it is the genetic regulation in the host, the interplay between virus or bacteria persistence and autoimmunity that produces the later phases of disease, the antigenic determinants responsible for inducing autoimmune disease, and the pathogenetic effector mechanisms. Infections agents cause pericarditis, but in 85% of cases it is "idiopathic". It has also been shown that persistent Clamydia pneumoniae, Porphyromonas gingivalis, and Helicobacter pylori infections cause host immunity and promote atherogenesis. A number of infectious agents have been suggested as potential triggers for primary biliary cirrhosis. Infections and vaccinations have also been linked to the pathogenesis of fibromyalgia syndrome, a common, chronic syndrome of widespread pain. Many factors are also responsible for fever of unknown origin such as: infections, autoimmunity disease, etc. However, it is difficult to determine a direct correlation between the infections agents in such a large group of diseases. The aim of this review is to analyze some of the controversies about the role of infections in autoimmune diseases.

Antibodies against beta2-glycoprotein I complexed with an oxidised lipoprotein relate to intima thickening of carotid arteries in primary antiphospholipid syndrome

To explore whether antibodies against β₂-glycoprotein I (β₂GPI) complexed to 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) and to oxidised low-density lipoproteins (oxLDL) relate to paraoxonase activity (PONa) and/or intima media thickness (IMT) of carotid arteries in primary antiphospholipid syndrome (PAPS). As many as 29 thrombotic patients with PAPS, 10 subjects with idiopathic antiphospholipid antibodies (aPL) without thrombosis, 17 thrombotic patients with inherited thrombophilia and 23 healthy controls were investigated. The following were measured in all participants: β₂GPI−oxLDL complexes, IgG anti-β₂GPI−oxLig-1, IgG anti-β₂GPI−oxLDL antibodies (ELISA), PONa, (para-nitrophenol method), IMT of common carotid (CC) artery, carotid bifurcation (B), internal carotid (IC) by high resolution sonography. β₂GPI−oxLDL complex was highest in the control group (p < 0.01), whereas, IgG anti-β₂GPI−oxLig1 and IgG anti-β₂GPI−oxLDL were highest in PAPS (p < 0.0001). In healthy controls, β₂GPI−oxLDL complexes positively correlated to IMT of the IC (p = 0.007) and negatively to PONa after correction for age (p < 0.03). PONa inversely correlated with age (p = 0.008). In PAPS, IgG anti-2GPI−oxLig-1 independently predicted PONa (p = 0.02) and IMT of B (p = 0.003), CC, (p = 0.03) and of IC (p = 0.04). In PAPS, PONa inversely correlated to the IMT of B, CC and IC (p = 0.01, 0.02 and 0.003, respectively). IgG anti-2GPI−oxLig-1 may be involved in PAPS related atherogenesis via decreased PON activity.

Logical Responses to Youth Who Run Away From Home: Implications for Psychiatric Mental Health Nursing

1. Runaway youths do not fit into a typical profile; they are adolescents of every race, ethnic group, and religious orientation; they are representative of every socioeconomic status and geographic location in America. 2. Psychosocial events including physical and sexual abuse are common antecedents to runaway behaviors. 3. Implications for psychiatric mental health nursing practice include working with community programs focused on reducing runaway episodes; implementing preventive measures focused on strengthening parenting and problem-solving skills for reducing conflict with families with adolescent children; and promoting responsible sexuality through adequate and responsible sex education and counseling.

Clinical significance of immunoglobulin A versus immunoglobulins G and M anti-cardiolipin antibodies in patients with systemic lupus erythematosus. Correlation with thrombosis, thrombocytopenia, and recurrent abortion

Serum levels of immunoglobulins (Ig) A, G, and M anti-cardiolipin (aCL) antibodies were determined by enzyme-linked immunosorbent assay in a group of selected systemic lupus erythematosus female patients. Patients were divided into three groups based on their clinical history of thrombosis with or without thrombocytopenia (group I), thrombocytopenia alone (group II), and neither of these (group III). After the aCL antibody levels were determined, the patients' obstetric histories of pregnancies and abortions were reviewed. A high incidence of one or more abortions was seen only in group I patients. A high prevalence of elevated levels of IgA and IgG (but not IgM) aCL antibodies was observed in group I patients. However, among the patients in group II, only the levels of IgA aCL antibodies were increased. In both groups, the addition of the IgA aCL determination--to the classical IgG and IgM aCL assays--increased the prevalence of positive reactors in 31.6%. These results indicate that high levels of IgA aCL antibodies correlated better with thrombocytopenia than either IgG or IgM. Also, the importance of including the determination of IgA aCL antibodies to assess properly the risk of thrombosis, thrombocytopenia, and recurrent abortions in systemic lupus erythematosus patients is demonstrated.

Reduction of intra-oral demineralization of enamel after single exposures to sodium fluoride

Studies demonstrated the effects of single rinses with low concentrations of NaF on the intra-oral demineralization of enamel. Blocks of bovine enamel were covered with Streptococcus mutans IB1600, mounted in palatal appliances, and worn in the mouths of volunteers for specified times. Subjects rinsed with solutions of NaF, with or without sucrose. Demineralization was determined as changes in iodide penetrability (delta Ip) of the enamel, while the pH and F of the streptococcal plaque, and enamel F, were determined with ion-specific electrodes. Delta Ip was reduced by about 80% (from 14.5 +/- 2.7 to 2.8 +/- 2.3 units) when 250 micrograms F/mL was added to the sucrose rinse. Corresponding plaque pH's were 4.1 +/- 0.5 and 4.2 +/- 0.3, consistent with a lack of effect on bacterial acidogenesis. Protection against mineral loss was concentration-dependent. Administration of sucrose at different times after NaF revealed that the effect of F persisted for at least 60 min. Analyses of plaque F demonstrated an initial elevation and concentration within the cells, followed by a drop to stable, baseline values. Enamel F increased slowly to almost 500 micrograms/g enamel after 105 min. The protective effect of F appeared to be manifested in two stages, the first related to a high plaque F and the second to F that became incorporated into the enamel. Analysis of the data suggested that F was transferred from plaque to enamel during the experimental period.

Adolescents' attitudes toward mental illness and perceived sources of their attitudes: an examination of pilot data

This exploratory descriptive pilot study examined the attitudes of 89 Floridian adolescents toward mental illness and found significant differences according to gender and education about mental illness. Responses to social distance items showed that adolescents tended to be less accepting as they were proposed relationships that suggested greater intimacy with the mentally ill. The mass media, personal experience with someone who had a mental illness, and parents were perceived by the adolescents as the most important sources of their attitudes. The major implications for nursing practice with adolescents, and particularly in the school system, are discussed with suggested interventions.

Lack of correlation between food retention on the human dentition and consumer perception of food stickiness

When dental health professionals advise that sticky foods be avoided, it is left to the consumer to choose correctly among different foods. In this study, comparisons were made among consumer ratings of stickiness of 21 commercially available foods and objective measurements of tooth retention of each of the foods. No correlation was found between the two, and neither the rates of clearance of food particles from the teeth nor the rates of clearance of food-derived sugars from the saliva correlated with ratings of food stickiness. Cookies, crackers, and potato chips were most retentive, whereas caramels, jelly beans, raisins, and milk chocolate bars were among those poorly retained. Clearance rates appeared to vary inversely with initial retention. However, chocolate-caramel bars exhibited high initial retention and a very rapid rate of clearance from the teeth. The findings show that consumers cannot accurately assess the retentiveness of foods and, thus, the advise simply to avoid sticky ones is inadequate.

Prevention of sucrose-induced demineralization of tooth enamel by chewing sorbitol gum

Measurements were made of the effect of chewing sorbitol gum on the intra-oral demineralization induced by rinsing with 10% sucrose solutions. Blocks of bovine enamel were covered with a layer of Streptococcus mutans IB1600, and mounted on palatal appliances that were worn by five subjects for defined periods of time. Enamel demineralization was determined by following changes in iodide penetrability (delta Ip) of the enamel surfaces. Delta Ip increased to a maximum of about 15 units between 30 and 45 min, while the pH of the S. mutans plaque dropped to below 4 by 15 min. Plaque pH returned to 4.9 by 60 min. Chewing sorbitol gum after the sucrose rinse minimized further increases in delta Ip and brought about a more rapid return of the S. mutans plaque pH toward neutrality. The effect of chewing gum was greater when chewing was initiated earlier so that, when gum was given at five min after the sucrose rinse, demineralization was only 37% of that obtained without gum. The findings confirm earlier reports on the effect of gum on plaque pH, and directly demonstrate the profound protective effects that chewing sorbitol gum can have on tooth enamel.

Lymphocytotoxic antibodies and intermediate immune complexes in hypergammaglobulinemic purpura of Waldenström

Immune complexes, lymphopenia, and lymphocytotoxic antibodies were detected in two patients with hypergammaglobulinemic purpura of Waldenström. These abnormalities were further characterized in one patient. Ultracentrifugation analysis of this patient's serum showed an intermediate peak likely representing medium sized immune complexes. Circulating IgG-containing immune complexes (2-ME resistant Clq binding material) and IgM rheumatoid factor (2-ME sensitive) were also detected. A sequential study of cold reactive IgM lymphocytotoxic antibodies revealed a significant inverse correlation between antibody levels and peripheral lymphocyte counts. The possible implications of these findings in the pathogenesis of hypergammaglobulinemic purpura are discussed.

Immediate skin test reactivity to common aeroallergens in patients with respiratory allergies: a comparative analysis of allergen-induced skin reactions and their histamine controls

The results of the immediate skin test response to a panel of 16 common aeroallergens performed in a group of 659 consecutive patients with symptoms suggestive of a respiratory allergy were analyzed. A group of 108 healthy individuals served as control subjects. Ninety-four percent of the patients and 87% of the control subjects had at least one allergen-induced reaction (wheal greater than or equal to 2 by 2 mm). The prevalence of positive skin reactions to each aeroallergen was equally high in both groups. However, if a skin reaction is considered as positive only when an allergen-induced wheal is equal or larger compared to the 50% of the wheal obtained with the histamine control in that individual, 70% of the patients had positive skin reactions and only 38% of the control subjects were positive (p less than 0.05). Similarly, the prevalence rates to five aeroallergens (pollen, Fusarium, Mucor, Pullularia, and Curvularia) in the patient group were reduced to those levels observed with the control group, suggesting they are clinically less important. The age and not the sex influenced both the prevalence rates (p less than 0.001) and the mean size (p less than 0.01) of allergen and histamine-induced skin reactions. Lower prevalence rates and mean size values were observed in the youngest group (0 to 9 years). Moreover, there was an inverse relationship between lower skin reactivity with more younger subjects in our patient population. These results indicate that patients and healthy individuals have similar mechanisms for skin reactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Cryoglobulinemia and cutaneous vasculitis in human brucellosis

We report the occurrence of cryoglobulinemia and cutaneous vasculitis in three patients with brucellosis caused by Brucella melitensis. The isolated cryoglobulins were characterized as mixed polyclonal or type III. Brucella agglutinin activity was not detected in any of the cryoglobulins analyzed. However, the same agglutinin titer and the presence of precipitin lines of identity in immunodiffusion gels were observed in the supernatant of the cryoglobulins and the serum. Rheumatoid-factor activity was present in all the cryoprecipitates tested. Resolution of the purpuric lesions with therapy coincided with a decrease in serum cryoglobulins and, in one patient, with normalization of his serum C3 levels. These findings suggest that the immunological abnormalities manifested by our patients were the direct consequence of the brucellosis infection and provide additional evidence to support the role for immunological mechanisms in the pathogenesis of human brucellosis.

The hypocomplementemic urticarial-vasculitis syndrome: therapeutic response to hydroxychloroquine

We report a patient with hypocomplementemic urticarial-vasculitis syndrome. This case illustrates the continuum between urticaria and purpura characteristic of hypocomplementemic urticarial-vasculitis syndrome. Clq precipitin was demonstrated in the patient's serum and in the diethylaminoethylcellulose-ion exchange fraction containing only IgG. A skin biopsy specimen of urticarial and purpuric lesions demonstrated leukocytoclastic vasculitis and granular deposition of C3 and Clq in the basement membrane with IgA, IgM, C3, and Clq in postcapillary venules. Serial total hemolytic complement activity and Clq determinations were performed, and the response to several treatment regimens is presented. Symptomatic and serologic improvement was observed only with hydroxychloroquine.

Gastrointestinal involvement in leukocytoclastic vasculitis and polyarteritis nodosa

The records of 106 consecutive patients referred to the University of Colorado Medical Center (UCMC) vasculitis study group during a 5-yr period were evaluated for gastrointestinal (GI) manifestations attributable to vasculitis. There were 3 groups: 18 with leukocytoclastic vasculitis (LCV) on skin biopsy younger than 16 yr of age; 75 with LCV older than 16 yr of age; and 13 with polyarteritis nodosa (PAN). Significant GI manifestations at presentation or exacerbation of vasculitis occurred in 38 of 106 (36%) patients. These were more frequent in LCV patients younger than 16 yr (66%), than older LCV patients (26%) or PAN patients (46%). The commonest complaint was abdominal pain (79%), followed by nausea (63%), vomiting (37%) and diarrhea (23%). GI bleeding was present in 52% and acute abdomen in 21% of patients. No consistent radiologic findings were noted. Duodenal and peritoneal biopsies suggested vasculitis in 6 LCV patients. Seven exploratory laparotomies were performed in 4 LCV and 3 PAN patients. Intestinal infarction was found in 3 patients with PAN, but in one of the LCV patients. Two patients with LCV with an acute abdomen were not explored and responded promptly to iv corticosteroids. Thus, systemic vasculitis frequently involves the GI tract. In patients with LCV, recognition of this association and treatment with corticosteroids can avoid surgery. In our patients with PAN, however, acute abdominal signs indicated infarction requiring surgery and resection.

The requirement of viable thymocytes for species-specific attachment to and release from macrophages

The role of the thymocyte in its species-specific binding to macrophages has been explored. Although formalin treatment of macrophages resulted in loss of binding to thymocytes, formalin treatment of thymocytes did not have this effect. However, two differences between living and formalin-treated thymocytes were noted. Formalin-treated thymocytes bound to macrophages of any species whereas the binding of living thymocytes was species specific. Living thymocytes attained maximum binding in approximately 1 hr and then the fraction bound gradually diminished. Formalin-treated thymocytes remained bound to the macrophage and appeared to be phagocytized. Released thymocytes did not bind to fresh macrophages, but released macrophages bound to fresh thymocytes. The results suggest that the binding of thymocytes to macrophages results in maturation of thymocytes.

Immunological survey in high altitude: effect on antibody production and the complement system

In order to asses the effect of acute exposure to natural high altitude on some immunological mechanisms of mice, the primary response to SRBC was studied by the direct Hemolytic Plaque and Hemagglutination Tests. A control group was studied in Lima, Peru, 150 m. At high altitude (Ticlio, Peru, 4843 m), we found fewer spleen plaque-forming cells (PFC) and the maximal peak of PFC was delayed 1 day, as compared with the response at a lower altitude. Conversely, there was a higher serum concentration of 2-ME sensitive and resistant hemagglutinin antibodies at high altitude and the 19-S (2-ME sensitive) response was predominant during the first days at high altitude while the 7-S response was retarded. These results are interpreted as a stimulating effect of hypoxia on the 19-S antibody production rather than a cellular proliferation as far as the SRBC system is concerned. Serum concentrations of Igs G, M, A and the fraction C'3 of the Complement (B1C/B1A globulin) were determined in normal natives from three cities at different altitude levels: Morococha-Ticlio, 4680 m; La Oroya, 3700 m; and Tarma, 3051 m by the Radial Immunodiffusion Test. The serum concentration of C'3 was correlated with the total hemolytic activity of Complement (C'H50 method) in a group of natives from Morococha. The control group was of normal natives from Lima. No significant differences were found between resum concentration of Igs G, M and A in both groups, but there was a tendency for higher values of IgA at higher altitudes, and most sera in the high altitude group were above the normal IgG values for adults. The resum concentration of C'3 and the hemolytic activity of Complement were wound to be diminished in the high altitude group. These results are interpreted as an inhibitory effect of the altitude on the sequential activation and/or lysing capability rather than a reduction in the C'3 concentration.