Homologous Serum Research Articles

Avidin attachment to biotinylated amino groups of the erythrocyte membrane eliminates homologous restriction of both classical and alternative pathways of the complement

Lysis of avidin-coated biotinylated sheep red blood cells (RBC) via the classical pathway of homologous (sheep) and heterologous (guinea pig) complement has been studied. The minimal surface density of avidin inducing antibody-dependent lysis via the classical pathway is smaller than that inducing antibody-independent lysis via the alternative pathway. Heterologous lysis via the classical pathway does not depend on the mode of avidin attachment: both biotinylation of membrane amino groups and insertion of biotinyl-lipid into the membrane provide the same lysis of avidin-coated RBCs by guinea pig serum in the presence of anti-avidin antibody. Avidin-free sheep RBC sensitized with hemolytic anti-RBC antibody were lysed by guinea pig, but not by sheep serum, confirming high efficiency of homologous restriction of the complement. However, avidin-coated RBCs were lysed by homologous serum in the presence of anti-avidin antibody at low surface density of avidin attached. The elimination of the homologous restriction depends on the mode of avidin attachment: biotinylation of membrane amino groups provides antibodymediated lysis via the classical pathway of homologous complement, while insertion of biotinyl-lipid does not provide lysis.

Effects of individual and combined treatment with prostaglandins E2 and F2 alpha on progesterone secretion by ovine luteal cells supplemented with homologous serum lipoproteins in vitro.

Prostaglandin F2 alpha (PGF2 alpha) is a potent luteolysin, whereas prostaglandin E2 (PGE2) is generally luteotropic in vivo. To establish a model system for investigations of the mechanisms involved in these actions, we examined the effects of individual and combined treatment with PGE2 and PGF2 alpha on basal and ovine LH-stimulated progesterone secretion during long-term incubations conducted with and without supplemental homologous low-density lipoprotein (LDL) as substrate. Effects of both PGF2 and PGF2 alpha were concentration- and time-dependent and were further influenced by the presence of LDL and/or LH in medium. Neither of the prostaglandins exerted any significant effect before 48 h in culture, but distinctly different patterns of response to PGE2 and PGF2 alpha emerged thereafter. Low, but not high, concentrations of PGE2 increased progesterone secretion in the absence of LH, whereas PGF2 alpha (alone and in combination with PGE2) inhibited progesterone production in all medium formulations. The transcriptional inhibitor actinomycin effectively blocked the actions of PGF2 alpha, but had no effect on response to LH or PGE2. These data demonstrate that both the putative luteotropic actions of PGE2 and the potent, luteolytic effects of PGF2 alpha in vivo can be reproduced in long-term cultures of ovine luteal cells in vitro, and they suggest that the mechanism of PGF2 alpha-induced luteolysis may involve new protein synthesis.

Comparaison de Deux Antigénes de Nature polysaccharidique pour le Diagnostic Sérologique par ELISA de la Pleuropneumonie Porcine (Sérotype 5)

Two antigens of polysaccharidic nature were evaluated for their specificity in serodiagnosis of porcine pleuropneumonia (serotype 5). Recently, long chains lipopolysaccharides (LC-LPS) was shown to increase the specificity of the ELISA test for A. pleuropneumoniae serotype 5 compared to a saline extract of boiled-formalinized whole cells. Nevertheless, some cross reactions were noticed with LC-LPS. We have thus cleaved the LPS molecule at the ketosidic bond between the lipid A and the core. The lipid A was separated from the polysaccharide (PS) by centrifugation. With an indirect sandwich ELISA, it was possible to demonstrate that the PS yielded positive responses with homologous sera (serotype 5) and negative responses with heterologous sera (serotype 3 and undeterminated serotype). Overall, the use of the PS did not notably increase the specificity of the ELISA test. Since production of PS from LC-LPS and its separation from the lipid A is not simple, we do not recommend its use in serodiagnosis.

In vitro fertilization analysis of squirrel monkey oocytes produced by various follicular induction regimens and the incidence of triploidy.

An in vitro fertilization system utilizing squirrel monkeys was used to compare follicle-stimulating hormone, clomiphene citrate and prostaglandin E1 as follicular induction regimens, analyze culture medium characteristics, and examine the physiological phenomenon of polyspermy. Induction of follicular growth was poor with clomiphene citrate when compared to the control group and increased the incidence of atretic follicles at all levels tested. When prostaglandin E1 was administered, larger numbers of mature oocytes were recovered at laparoscopy. There was no difference in fertilization rate between the treatment and control groups. Homologous serum was an adequate protein source in TC-199 fertilization medium for squirrel monkey oocytes. Although the rate of triploidy was increased with in vitro fertilization, there was no relationship between sperm concentration and the incidence of polyspermy. These findings demonstrate that the squirrel monkey is a valuable primate system for studies of in vitro fertilization and preimplantation development. © 1993 Wiley-Liss, Inc.

A finger-stick assay for determination of immunity to hepatitis A: a preliminary report

A simple and reproducible method for determining immunity to hepatitis A has been developed, using whole blood obtained by finger-stick and fixed on small discs. This method permits screening of large populations of candidates prior to active or passive immunization, avoiding the discomfort and difficulty of venipuncture, especially in children. The technique involves a finger-stick with a blood lancet, collection of 20 microliter whole blood on a paper disc which is then dried at room temperature. Perforated discs are incubated with phosphate buffered saline and the eluate is then tested for anti-HAV using the HAVAB assay. Results of anti-HAV assays from finger-stick samples obtained from adults and from children, showed 100% conformance with the homologous venous serum samples obtained at the same time. The lower threshold for detection of anti-HAV by this method is currently below 100 mIU/ml, as compared to 20 mIU/ml by the modified HAVAB method. In conclusion, we have developed a simple and reliable method for determination of immunity to HAV using whole blood obtained by finger-stick and fixed on paper discs. Samples can be collected under field trial conditions, without immediate need for laboratory facilities for separation and storage of serum samples. This sampling method, which is mainly intended for qualitative determination of anti-HAV in HAV immune subjects, especially under field trial conditions, is rapid, economical, efficient and acceptable to populations that are generally apprehensive of conventional venipuncture specimen collection methods.

Effects of substrate supplementation with hydroxycholesterol analogues and serum lipoproteins on ovine luteal cell progesterone secretion in vitro: demonstration of prostaglandin F2 alpha luteolytic actions in a defined model system.

In an attempt to establish a defined model system for studies aimed at elucidating the mechanism of PGF2 alpha action, we examined the effects of medium supplementation with soluble hydroxycholesterol analogues, alone and in combination with ovine luteinizing hormone (oLH) in the presence and absence of PGF2 alpha, on progesterone secretion by mixed ovine luteal cells in vitro. In short-term cultures (2-6 h), supplementary 22R-hydroxycholesterol (22R-OHC; 0.16-20 micrograms ml-1) increased (P < 0.05) progesterone production in a dose-dependent manner, whereas similar concentrations of 22S-hydroxycholesterol (22S-OHC) and 25-hydroxycholesterol (25-OHC) had little effect. In incubations of < or = 24 h duration, 22R-OHC (1 micrograms ml-1) dramatically increased progesterone secretion, whereas oLH (100 ng ml-1) in the presence or absence of PGF2 alpha (250 ng ml-1) had no consistent effects, alone or in combination with 22R-OHC. In contrast, 22R-OHC (1 micrograms ml-1) alone had no effect in long-term incubations (72-192 h), nor did treatment with oLH (100 ng ml-1) in the presence or absence of PGF2 alpha (250 ng ml-1) in the absence of 22R-OHC. Together, however, 22R-OHC and oLH stimulated (P < 0.05) progesterone secretion, a synergistic effect consistently inhibited (P < 0.05) by PGF2 alpha. Equimolar (2.5 mumol l-1) concentrations of 22R-OHC and homologous serum low- or high-density lipoprotein cholesterol exhibited comparable capacities to maintain progesterone secretion in long-term cultures (24-168 h), with and without gonadotrophin (oLH or human chorionic gonadotrophin, 100 ng ml-1) stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Transfer of Experimental Autoimmune Thyroiditis by in Situ Perfusion of Thyroids with Immune Sera

The role of autoantibodies in the pathogenesis of autoimmune thyroiditis (AT) still remains poorly understood. Serum transfer experiments in experimental AT (EAT) and spontaneous AT (SAT) animal models frequently did not succeed or only resulted in minor thyroid lesions. The inconsistent results may have arisen because of technical problems inherent in serum transfer, the major of which is to obtain high enough concentrations of autoantibodies over long enough periods at the potential site of tissue injury. An attempt was made to circumvent this hurdle by repeated in situ perfusions of the rabbit thyroid via the superior thyroid artery. In situ perfusion of rabbit thyroids with high-titered homologous sera reactive with saline thyroid extract indeed led to thyroiditis characterized by granular deposits of rabbit IgG and C3 in the thyroid follicular basal laminae, cellular infiltrates consisting of mononuclear cells and granulocytes, destruction of the thyroid follicular architecture, and focal fibrosis. Perfusion with control sera lacking thyroid-reactive antibodies did not lead to thyroid lesions. These results demonstrate that humoral antibodies can induce severe AT comparable to actively induced thyroiditis.

Human serum amyloid P-component (SAP) selectively binds to immobilized or bound forms of C-reactive protein (CRP)

The two homologous human pentraxins, C-reactive protein (CRP) and serum amyloid P-component (SAP), specifically bind to each other only when the CRP is in an immobilized form bound to one of its ligands or to an antibody. CRP did not bind to immobilized SAP. The binding of SAP to immobilized forms of CRP was Ca 2+-dependent and of sufficient affinity to occur in the presence of serum of serum or purified serum proteins. SAP bound preferentially to a synthetic peptide corresponding to the Ca 2+-binding region of CRP. Monoclonal antibodies to a synthetic peptide corresponding to the Ca 2+-binding region selectively inhibited the binding interaction. Proteolytic cleavage of CRP between residues 146 and 147 within the Ca 2+ binding region abolished the SAP-binding site; however, the intact subunits of the pentameric CRP were capable of binding SAP. The significance of the binding interaction is that it may serve as the basis for localization of SAP to sites of tissue damage or repair, sites where CRP is selectively deposited.

Differences of draining lymph node cell proliferation among mice, rats and guinea pigs following exposure to metal allergens

Contact sensitivities of three well known metal allergens (nickel sulfate, potassium dichromate and cobalt chloride) were examined using the local lymph node assay in CBA/N mice, F344 rats and Hartley guinea pigs. The effect of various species sera on lymph node cell (LNC) proliferation was also investigated. Exposure to potassium dichromate and cobalt chloride induced significant LNC proliferative responses in the three species. The LNC responses to potassium dichromate in the rats were higher than those in the mice and guinea pigs. Mice exhibited the highest response to cobalt chloride among the three species, whereas, exposure to nickel sulfate failed to induce a marked LNC proliferation. Increased draining lymph node weights and LNC numbers were also observed following exposure to the metal salts. However, these parameters were less sensitive compared with the LNC proliferative response. There was a large difference in the lymph node weight between individual guinea pigs. The [ methyl- 3thymidine incorporation into LNC of each species cultured in the presence of the homologous serum in vitro was lower than in the presence or absence of fetal calf serum. However, there was no significant difference in stimulation indices among the different culture conditions. The local lymph node assay may be performed in rats as well as in mice for the detection of metal allergens.

Influence of Actinobacillus pleuropneumoniae serotype 2 and its cytolysins on porcine neutrophil chemiluminescence

The effects of Actinobacillus pleuropneumoniae serotype 2 and its metabolites on the oxidative activity of porcine neutrophils were studied by using a chemiluminescence technique. Viable A. pleuropneumoniae stimulated the production of oxygen radicals by neutrophils. After having reached a peak value, the oxidative activity decreased until a total inhibition of the oxidative activity of the neutrophils was achieved. All effects were neutralized with homologous convalescent-phase pig sera which had been adsorbed by heat-inactivated A. pleuropneumoniae. Inactivated bacteria and bacteria in the presence of chloramphenicol each had no influence on the oxidative activity of neutrophils. In contrast, a heat-labile factor in A. pleuropneumoniae culture supernatants stimulated and inhibited the oxidative activity of the neutrophils in a dose-dependent manner. Undiluted and low dilutions of culture supernatants were toxic for the phagocytes, while high dilutions stimulated the oxygen radical production of the neutrophils. These effects were neutralized with homologous convalescent-phase pig sera. In order to investigate whether the heat-labile factors in the culture supernatant could be cytolysins, we repeated the experiments with cytolysin II and cytolysin III produced by recombinant Escherichia coli. It was demonstrated that stimulation and inhibition could be reproduced by both cytolysins. In conclusion, the observations made in this study showed that A. pleuropneumoniae secretes heat-labile metabolites that stimulate neutrophil-oxidative metabolism at relatively low concentrations and kill the neutrophils at higher concentrations. Cytolysins may be responsible, at least in part, for these effects.

Specificity of the carbon immunoassay (CIA) test for the diagnosis of Toxoplasma infections

A rapid and low cost procedure, the carbon immunoassay (CIA) test, was evaluated for the diagnosis of Toxoplasma gondii infections. Using a closely related parasite ( Besnoitia jellisoni) as antigen, and homologous or heterologous immune sera, it was demonstrated by light and electron microscopy that CIA is a very reliable and specific test. As it is neither expensive nor time-consuming, it can be recommended for general and routine laboratory use.

Fast Lysis by Complement and Uptake by Liver of Avidin-Carrying Biotinylated Erythrocytes

The fate of 51Cr-labelled avidin-carrying biotinylated erythrocytes after intravenous injection in the rat was examined. Surface amino groups of the erythrocyte membrane were modified by biotin N-hydroxysuccinimide ester. The biodistribution and stability of biotinylated erythrocytes in the blood were similar to those of non-biotinylated cells. Both types of cells circulated in the bloodstream for prolonged periods of time without substantial lysis (about 2-3% of injected radioactivity per g of blood for 24-48 hours, no more than 2% of lysis). Both types of erythrocytes were cleared by the spleen. The clearance of biotinylated cells was faster and more pronounced (peak of spleen uptake at 3 hours after injection, up to 35% of injected radioactivity per g of spleen), than that of nonbiotinylated cells (peak of spleen uptake at 24 hours after injection, up to 25% of injected radioactivity per g of spleen). Attachment of avidin to biotinylated cells results in extremely rapid lysis and clearance from the bloodstream (0.17% of injected radioactivity per g of blood 30 min after injection, 100% lysis). Radioactivity was rapidly cleared by the liver (up to 80% of injected dose per g of tissue, 70% per organ). Uptake by the spleen plays only a minor role in the clearance. Considerable lung uptake of avidin-carrying biotinylated erythrocytes was observed. Avidin-carrying biotinylated erythrocytes were lysed by fresh homologous serum in vitro in contrast to biotinylated and native cells. Lysis was eliminated by pretreatment of serum with EDTA or heating, which indicates a complement-dependent mechanism of lysis.

Impaired hexose uptake by diploid skin fibroblasts from galactosaemic patients. Connection with cell growth and amino acid metabolism, and possible bearing on late-onset clinical symptoms.

In skin fibroblasts of patients presenting with galactosaemia, either from galactose 1-phosphate uridyltransferase or galactokinase deficiency, a deficit in extracellular glucose utilization was observed. This deficit was constant over 3 weeks of continuous cell growth in a medium containing 5.5 mmol/L glucose as the only hexose, and homologous serum. Levels of glucose utilization by deficient skin fibroblasts were stable at about 65-70% of the glucose utilization of control normal skin fibroblasts. Cell morphology was normal, and cell growth was subnormal during this period. However, the energy provision appeared sufficient for cellular needs since cell growth in this glucose medium was observed not to depend on the presence of extracellular glutamine. In contrast, glutamine was required for growth of galactosaemic fibroblasts cultured in medium containing 5.5 mmol/L galactose. If expressed in many cell types, this impaired glucose uptake would be expected seriously to damage highly glucose-dependent tissues such as the central nervous system. This might be of relevance to the persistent neurological damage observed in many galactosaemic patients in spite of their compliance with an early strict galactose-free diet.

Obtenção e avaliação de antígenos de Aspergillus fumigatus

Antigens from three strains of Aspergillus fumigatus (354, 356, and JIG) and an antiserum against the mixing of these antigens have been produced, and evaluated immunochemically. The antigens were obtained through a modified Coleman & Kaufman technique (culture filtrate concentrated by acetone). Analysis by the immunodiffusion test (ID) against homologous serum has yielded 100% sensitivity (with the studied sera). Concerning heterologous sera we found reactivity with a serum of a patient of candidiasis and another with histoplasmosis. The same result was obtained with a reference antigen in immunodiffusion, showing similar standards of response. Titration of the antiserum by ID and counterimmunoelectrophoresis showed a title of 1:32, and by complement fixation (micro-technique) a title of 1:128. Using immunoelectrophoresis (IEF), the produced antiserum yielded 8 lines of precipitation (5 in the anodic pole and 3 in the cathodic one). In SDS-PAGE at 12.5% the antigen has presented a rather complex electrophoretic profile (26 proteic subunits with a molecular weight ranging from 18 a > 100 kDa). Immunogenicity of the antigen was observed in all fractions of SDS-PAGE when the immunoblotting against the antiserum was carried out.

Stimulation and suppression of the oxygenation activity of porcine pulmonary alveolar macrophages by Actinobacillus pleuropneumoniae and its metabolites

Summary The effects of Actinobacillus (Haemophilus) pleuro-pneumoniae and its metabolites on the oxygenation activity of porcine pulmonary alveolar macrophages (pam) were studied, using a chemiluminescence technique. Actinobacillus pleuropneumoniae strains of serotypes 2, 3, and 9 in a dose of 1, 10, and 100 colony-forming units/ macrophage first stimulated the oxygen radical production of pam. After having reached a peak value, oxygenation activity decreased, finally resulting in total suppression of pam. All these effects were neutralized by homologous convalescent pig sera that had been adsorbed onto inactivated A pleuropneumoniae strains. Moreover, cross-neutralization was shown between serotypes 2 and 3. Inactivated A pleuropneumoniae strains did not influence the oxidative activity of pam. Undiluted and lower dilutions of sterile A pleuropneumoniae culture supernatants were toxic for pam, whereas higher dilutions of the supernatants stimulated oxygen radical production of the macrophages. These effects were heat-sensitive and were neutralized by homologous convalescent pig sera. Cross-neutralization was shown between serotypes 2 and 3. These findings indicated that stimulation and inhibition of the oxygenation activity of pam are attributable to heat-sensitive metabolites produced by A pleuropneumoniae.

Expression of the complement regulatory proteins CD21, CD55 and CD59 on Burkitt lymphoma lines: their role in sensitivity to human serum-mediated lysis.

On a panel of nine human B cell lines we showed that the expression of the complement regulatory factors complement receptor type 2 (CR2; CD21), decay-accelerating factor, (DAF; CD55) and homologous restriction factor (HRF20, CD59) is not correlated. All lines expressed DAF, six lines carried detectable amounts of CR2 and three carried HRF20. Upon incubation in human serum, under conditions which allowed the activation of complement through the alternative pathway, the CR2-carrying lines bound C3 fragments and two of them (Ramos and one of its two sublines) were damaged. These two lines had the lowest DAF expression, less than 50% of the cells reacted with the IA10 monoclonal antibody. By modulating the expression of the complement regulatory molecules, the lytic sensitivity of the B cell lines could be altered. Blockade of DAF on the HRF20-, CR2+ lines with the specific monoclonal antibodies increased their sensitivity to lysis by human serum. With the DAF- and HRF20+ cells significant lytic effect was obtained only when they were pretreated with both of the specific antibodies. Interferon-gamma or tumor necrosis factor-alpha treatment elevated the amount of CR2 on the low-CR2 expressor line (Ramos/HR1K) which thereafter bound higher amounts of C3 fragments and was lysed when incubated in human serum. This line had relatively low DAF level and lacked HRF20. The cytokine treatment did not alter the expression of these molecules. The CR2+ Ramos and the CR2- Rael cells were treated with 5-azacytidine which induced HRF20 and increased DAF expression. In parallel with this change Ramos cells became resistant to C-mediated lysis. The experiments with the panel of human B cell lines showed thus that cytolysis through activation of complement in homologous serum can be regulated at several steps by cell surface molecules. While expression of CR2 was required for C3 fixation, DAF and HRF20 inhibited lysis. By independent modulation of the quantities of these molecules, cells acquired or lost their sensitivity.

Factors influencing the rate of preantral and antral growth of mouse ovarian follicles in vitro.

The development of a culture system for individual mouse ovarian follicles using a low concentration of homologous serum, human follicle-stimulating hormone (hFSH) and a simple combination of growth factors is reported. Preantral follicles, 150 microns in diameter, with thecal cells attached were isolated mechanically. After 6-7 days on a Millicell membrane, a high proportion of the preantral follicles cultured individually with hFSH grew to morphologically normal large antral follicles (400-500 microns in diameter) with high oestradiol secretion. Without hFSH, the follicles grew to approximately 275 microns diameter in 6 days, but did not form antra or secrete oestradiol. The growth trajectory (overall pattern of growth formed by daily measurements of diameter) of each follicle was recorded and used as a measurement of response to experimental variation of culture conditions. The rapidly growing follicles were morphologically normal, but those that grew more slowly showed some abnormality or atresia and secreted less oestradiol. Follicles cultured in groups without being in direct contact with each other showed much poorer growth than those grown individually, but the inhibition was not uniform and some follicles grew larger than others in the group. Follicles that contacted each other directly in culture tended to fuse into one mass and their growth was substantially inhibited. Even under these conditions, one follicle often continued to grow slowly while the others degenerated. Such alteration of growth patterns suggests interfollicular paracrine control and may be a means of three-dimensional spacing of follicle growth within the ovary, as well as part of the mechanism of follicle selection. The dose-response curve based on the mean growth trajectory of follicles cultured individually, produced increasing rates of growth with 12.5-100 miu hFSH ml-1. Higher concentrations of hFSH did not increase growth rate further, but oestradiol secretion continued to increase with increasing hFSH up to the maximum used (2000 miu ml-1).

Inhibition of the proteolytic activity of hemorrhagin-e from Crotalus atrox venom by antihemorrhagins from homologous serum

Antihemorrhagic proteins from Crotalus atrox serum were tested for their ability to inhibit the proteolytic activity of the hemorrhagic toxin-e from Crotalus atrox venom and of several other proteolytic enzymes: trypsin, collagenase and thermolysin. The antihemorrhagic proteins inhibited the proteolytic activity of hemorrhagin-e when tested on gelatin type I and collagen type IV, the proteolytic activity of trypsin on photofilm gelatin and the proteolytic activity of whole venom when tested on azocollagen and photofilm gelatin. The antihemorrhagins failed to inhibit the proteolytic activity of trypsin when tested on the specific synthetic substrate N-acetyl- dl-phenylalanine-β-naphthyl ester (APNE), the activity of microbial collagenase on N-(3-[2-furyl]acryloyl)-Leu-Gly-Pro-Ala (FALGPA) or on azocollagen and the activity of thermolysin on N-(3-[2-furyl] acryloyl)-Gly-Leu amide (FAGLA). It is tentatively suggested that the antihemorrhagins from snake blood serum are proteinase inhibitors that under-went specialization towards the neutralization of the proteolytic activity of hemorrhagic toxins.

Adherence of Helicobacter pylori to HEp-2 cells

The adherence of 25 strains of Helicobacter pylori was evaluated in HEp-2 cells. These bacterial isolates, obtained from Chilean patients with gastric disorders, were also tested for haemagglutination of human red blood cells. Adherence of HEp-2 cells was expressed as a common property of all strains, irrespective of whether the cultures were grown on semi-solid or in liquid media. Previous reports that haemagglutinating activity was present in cells grown only on semi-solid media were confirmed. Adherence to HEp-2 cells was suppressed when bacterial cells were pretreated with homologous or heterologous whole human serum, containing specific antibodies of H. pylori. Adherence remained unaltered when bacterial cells were similarly treated with normal serum lacking specific antibodies. These observations imply that adhesions are expressed in vivo and suggest that an adherence mechanism, not depending on the expression of specific haemagglutinin antigen, operates for H. pylori.

Brugia pahangi: Effects of maternal filariasis on the responses of their progeny to homologous challenge infection

Granulomatous lesion formation and immune responses to Brugia pahangi infections were compared in age-matched male progeny of homologously infected and uninfected female jirds. Infections initiated in 2-week-old offspring yielded X ± SD adult worm recoveries of 6.0 ± 5.7 and 4.2 ± 5.4 in offspring from infected or uninfected mothers, respectively. Infections initiated in 4-week-old offspring resulted in an X ± SD recovery of adult worms of 11.3 ± 11.3 and 10.2 ± 5.8 in offspring from infected and uninfected mothers, respectively. The ratio of intralymphatic thrombi per intralymphatic worm was similar between infected offspring from infected or uninfected mothers within experiments. Areas of granulomas around B. pahangi antigen-coated beads embolized in the lungs were not significantly affected by maternal origin in infected or uninfected progeny. Offspring infected at 2 or 4 weeks of age from infected mothers exhibited significantly reduced titers of serum IgG antibodies to Brugia antigens at 5–8 weeks postinfection compared to infected offspring of uninfected mothers. Infected offspring from infected mothers also had significantly fewer splenic IgG plaque-forming cells to B. pahangi antigens at 5 weeks postinfection than similarly infected offspring from uninfected mothers. Western immunoblot analysis indicated qualitative and quantitative reductions in serum antibody reactivity to adult B. pahangi antigens in infected progeny of infected females compared to age-matched infected controls. Reduced homologous serum antibody responses in progeny exposed to maternal B. pahangi infection suggest that maternal immunoregulation to filarial antigens may occur. Reduced antibody responsiveness to B. pahangi antigens observed in infected offspring from infected mothers, however, had no demonstrable effect on adult worm burdens, microfilaremias, lymphatic lesion formation, or antigen-specific granulomatous inflammatory responses compared to infected progeny of uninfected mothers.