Detection of antibodies to a recombinant Cryptosporidium parvum p23 in serum and feces from neonatal calves

Passive transfer of maternal antibodies via colostrum is important to protect newborn ruminants against microbial pathogens. In this study, 10 sets of calf serum, a sample of the colostrum fed to the calf, and serial fecal samples through the first 6 days after birth were collected from arbitrarily selected newborn Holstein heifers. A recombinant Cryptosporidium parvum p23, termed rC7, was used to determine whether anti-C. parvum antibodies can be detected in clinically normal neonates. The results demonstrated that serum, the associated colostrum, and fecal samples contained anti-rC7 antibodies. IgM and IgG1 anti-rC7 tended to be present in highest titers. The presence of specific antibodies to C. parvum was confirmed using Western blots of purified sporozoite membranes probed with serum and colostral whey. Collectively, the results indicated that neonatal calves had antibodies to C. parvum as early as 1 day after birth and suggested that the antibodies were passively transferred.     

Protective effect of colostrum in Mycoplasma pneumoniae infection induced in infant mice

The immunological responses and mechanism of maternal immunity in Mycoplasma pneumoniae infection of mice were investigated. ICR female mice, 4 weeks old, and infant mice, 2 to 4 days old, were infected with M. pneumoniae. Anti-M. pneumoniae antibodies in serum and colostrum were determined by enzyme-linked immunosorbent assay. The specific IgG antibody production persisted for 9 months or longer in both the young and infant mice. These infected mice were protected from rechallenge with M. pneumoniae. In addition, the infected dams conferred passive immunity on their offspring. The infant mice born to uninfected normal dams were protected from the challenge with M. pneumoniae when fed by infected foster dams. Conversely, the infant mice born to infected dams were not protected from the challenge with M. pneumoniae when the infants were fed by uninfected dams. The specific IgG antibody appeared in serum of infant mice inoculated orally with M. pneumoniae-infected mouse serum and the infants were protected from challenge with M. pneumoniae, while the infants given protein A-absorbed serum were not protected from the challenge. These results suggest that one of the factors involved in the resistance of infant mice to M. pneumoniae infection is the specific IgG antibody present in the colostrum rather than the result of transplacental transfer.     

Serum immunoglobulin type G concentrations in calves produced by IVF and delivered by elective cesarean section

Colostrum ingestion by neonatal calves is widely recognized to provide passive transfer of immunity. In this study immunoglobulin absorption from colostrum was evaluated in 54 IVF-produced calves. The IVF calves were delivered by Cesarean section on Days 275 to 277 of gestation, 24 h after the dams had been administered 30 mg dexamethasone. The calves suckled bottles or were force-fed 6 L of colostrum in the first 12 h of life. Colostrum was obtained from the first post-calving milking of recipient dams or from frozen storage reserves if dam secretion was not adequate. Immunoglobulin type G (IgG) content of both sources of colostrum was determined. Serum samples from the calves were collected at 0, 12 and 24 h of age and analyzed for IgG. Twenty dairy calves born vaginally served as the controls and were subjected to the same colostrum management protocol except that the colostrum was obtained only from frozen post-calving milk of dairy cows from the same farm. The control calves were also subjected to the same sampling protocol. The IVF group of calves ingested more IgG (P < 0.0001) and absorbed more IgG by 24 h of age (P < 0.0001) than their control group counterparts. Absorption of IgG was analyzed by comparing the g/kg body weight of IgG with serum IgG values at corresponding times after birth. Colostrum absorption efficiency was the same for both IVF and control groups of calves at 12 and 24 h of age. There was a maximum IgG dose above which additional increases in serum IgG were not realized. The slightly premature, Cesarean delivered IVF calves absorbed IgG from colostrum similarly to control calves delivered vaginally.     

A Modified IF-test to Demonstrate IgM Antibodies to Babesia Divergens of Cattle

An IF–test modified to increase sensitivity was used to detect the presence of Babesia divergens specific IgM antibodies. It consisted of three steps: (1) the incubation of Babesia antigen with test serum, followed by; (2) its incubation with protein A; and (3) the addition of rabbit anti-bovine IgM bound to protein A, which was bound with FITC. Compared to the conventional IF–technique, this modified IF-technique detected bovine anti-Babesia-IgM in test serum at a two–fold lower dilution and with a diminished background staining. This modified IF-technique improves the possibilities for studying class Μ antibody in the serum of cattle which have been infected with B. divergens. It is possible to determine whether a calf s antibody response is due to maternally transmitted antibodies or actively acquired antibodies by determining the presence of each of the classes of immunoglobulin against B. divergens present in the calf s serum.     

Colostrum from Cows Immunized with a Vaccine Associated with Bovine Neonatal Pancytopenia Contains Allo-Antibodies that Cross-React with Human MHC-I Molecules

In 2006, a new haemorrhagic syndrome affecting newborn calves, Bovine Neonatal Pancytopenia (BNP), was reported in southern Germany. It is characterized by severe bleeding, destruction of the red bone marrow, and a high case fatality rate. The syndrome is caused by alloreactive, maternal antibodies that are ingested by the calf with colostrum and result from a dam vaccination with one particular vaccine against Bovine-Viral-Diarrhoea-Virus. Because bovine colostrum is increasingly gaining interest as a dietary supplement for human consumption, the current study was initiated to elucidate whether BNP alloantibodies from BNP dams (i.e. animals that gave birth to a BNP-affected calf) cross-react with human cells, which could pose a health hazard for human consumers of colostral products. The present study clearly demonstrates that BNP alloantibodies cross-react with human lymphocytes in vitro. In agreement with previous reports on BNP, the cross-reactive antibodies are specific for MHC-I molecules, and sensitize opsonised human cells for in vitro complement lysis. Cross-reactive antibodies are present in serum and colostrum of individual BNP dams. They can be traced in commercial colostrum powder manufactured from cows immunized with the vaccine associated with BNP, but are absent from commercial powder manufactured from colostrum excluding such vaccinated cows. In humans alloreactive, MHC-I specific antibodies are generally not believed to cause severe symptoms. However, to minimize any theoretical risk for human consumers, manufacturers of bovine colostrum for human consumption should consider using only colostrum from animals that have not been exposed to the vaccine associated with BNP.     

Changes in serum and plasma proteins and in IgG and IgM antibodies in calves experimentally infected with sarcocystis from dogs.

Fifteen calves were used in three experiments to determine changes in serum and plasma proteins and IgG and IgM levels after oral inoculation with Sarcocystis sporocysts from dogs. Total serum or plasma protein levels in inoculated calves decreased during the acute phase of infection (4 to 5 weeks after inoculation) and then increased and became greater than the levels of control calves 7 to 8 weeks after inoculation. The initial decrease in total protein reflected reduced serum albumin and the subsequent increase reflected increased immunoglobulin levels. Immunoglobulin levels increased in both IgM and IgG fractions. Specific antibody activity against Sarcocystis antigen was 6 to 9 times greater in the IgM than in the IgC fraction 5 weeks after inoculation, but IgG activity became approximately 17 to 27 times greater than IgM activity 10 to 13 weeks after inoculation.     

Efficacy of hyperimmune bovine colostrum for prophylaxis of cryptosporidiosis in neonatal calves

Twelve neonatal calves were experimentally infected with oocysts of Cryptosporidium parvum. Six calves in group A fed hyperimmune colostrum at birth had significantly less diarrhea and shed oocysts for less time than did 6 calves in group B fed colostrum from cows that were not hyperimmune. Calves in group A had diarrhea for 0-4 days (means = 2.3 days), whereas calves in group B had diarrhea for 4-6 days (means = 5.0 days). Calves in group A shed oocysts for 4-9 days (means = 6.2 days), whereas calves in group B shed oocysts for 7-11 days (means = 8.5 days). These findings indicate that passive lacteal immunity conferred partial protection against cryptosporidiosis. Whether such protection was provided by the immunoglobulins that were highly elevated in the colostrum (greater than 1:200,000 for IgG1, IgM, and IgA) and constituted a large part of the circulating antibody in the calves, or by other biologically active factors, such as cytokines, is undetermined.     

Humoral antibody response to cattle to formalinized Staphylococcus aureus vaccine.

Five cows were inoculated intradermally with formalinized Staphylococcus aureus suspension in Freund's complete adjunvant and the development of the humoral antibody response was followed as judged by the agglutination titer of sera, at various intervals post inoculation. Highest titers were observed at 78-87 days post inoculation. Agglutinating activity was found in IgM and IgG fractions (IgG1 and IgG2) of both serum and colostrum. The agglutinating activity of colostrum was significantly higher at 12 than at 24 and 36 h, post partum. However, no such activity was detected in either normal cow serum or colostrum against S. aureus.     

Studies on Immunoglobulins and Trypsin Inhibitor in Colostrum and Milk from Sows and in Serum of Their Piglets

The concentrations of IgG, IgM, IgA and the specific sow colostrum trypsin inhibitor (SCTI) were measured by radial immunodiffusion in colostrum and milk samples from sows and in serum samples from their offspring during the suckling period. A clear time dependence was found for all the measured variates in both whey and serum. Statistically significant positive correlations were found between, on the one hand, concentrations of IgG and IgA, but not IgM, in sera from 39 suckling piglets 1 and 3 days old, and, on the other hand, concentrations of the same immunoglobulins and of the trypsin inhibitor in maternal colostrum (n = 7). Multiple regression analyses showed that at day 1 and day 3 the levels of both IgG and IgA in serum samples from the suckling piglets were positively influenced by both the SCTI and the IgG or IgA contents in maternal colostrum.     

Antibody production in rats vaccinated with inactivated Sendai virus (author's transl)

Adult male and female rats were inoculated with tween 80-ethylether-formalin-ultraviolet inactivated Sendai virus (Sv-V) and examined for the production of hemagglutination inhibition (HI) antibody. There were no significant differences in the antibody titers between males and females, and among the various routes of inoculation except for the intranasal which was not effective. The antibody became detectable 7 days after a single inoculation with 10(5) HAU of Sv-V. The antibody titer, which had its peak 21 days after the inoculation, persisted for 200 days and declined gradually thereafter. The HI antibody titers were correlated with inoculated Sv-V doses and a predominant booster reaction with the vaccine was observed. Maternal antibodies were detected in sucklings born to dams hyperimmunized with the vaccine. The titers were similar to those of the dams until 3 weeks after birth but declined rapidly after weaning at 4-week-old. The titers of fetuses and neonates before suckling were significantly lower than those of the sucklings.     

Passive immunization against transmissible gastroenteritis virus in piglets by ingestion of milk of sows inoculated with attenuated virus.

Pregnant sows were inoculated with the attenuated strain, TO--163, of swine transmissible gastroenteritis virus. Suckling piglets born from them received challenge inoculation with the virulent virus at 3 days after birth, and examined for ability to prevent infection and the immunoglobulin (Ig) classes of antibody in milk. A pregnant sow was inoculated intramuscularly with a dose of 10(8.0) TCID50 and intranasally with a dose of 10(9.3) TCID50 of attenuated virus. Piglets born from it suffered from diarrhea after challenge inoculation, but none of them died eventually. Their dam was also affected with diarrhea for 4 to 7 days after challenge inoculation of them. Another pregnant sow was inoculated twice with 10(9.3) TCID50 of attenuated virus, first by the intramuscular and secondly by the intranasal route. Of nine piglets born from it, one excreted soft feces after challenge inoculation, but all survived to grow normally. Their dam manifested no clinical symptoms at all after challenge inoculation of them. The higher the titer of virus inoculated into pregnant sows, the higher the neutralizing antibody titer in serum and milk of the sows after farrowing. The puerperal sow which had received two doses of 10(9.3) TCID50 each of attenuated virus by the intramuscular and intranasal route, respectively, presented the highest neutralizing antibody titer of all the inoculated sows. This titer was 2,048 in serum and 14,183 in colostrum immediately after farrowing. In that sow IgG was the main class of immunoglobulins in neutralizing antibody in milk. Even the IgA antibody titer of that sow was higher than that of any other sow which had been administered with virus of low titer. It was 392 and 19 3 and 9 days, respectively, after farrowing.     

Effect of treatment with formaldehyde and formic acid on immunoglobulin content of stored bovine colostrum

Colostrum was collected from the first postpartum milking of German Black Pied cows. Four independent pools of colostrum were made and the following preservation methods replicated in each pool, viz. formaldehyde treatment, 0.1% (F1) and 0.05% (F2); formic acid treatment, 0.5% (FA1) and 0.1% (FA2) and an untreated control (NF). All the colostrum batches were stored at an average incubation temperature of 28°C in 200-ml plastic bottles. Samples were collected from every batch on Day 0 (before incubation) and subsequently after every week for 4 weeks. All the samples collected were analysed for immunoglobulin (IgG1, IgG2, IgA and IgM) content of the whey fraction using the single radial immunodiffusion (SRID) method. pH was measured using a glass electrode pH meter.Formaldehyde treatment of colostrum maintained almost constant immunoglobulin levels under the conditions of this experiment. There were significant drops in the mean IgG1 (P < 0.0001) and IgM (P < 0.005) contents in the control (NF) and the formic acid treated (FA1 and FA2) colostrum. The levels of IgA and IgG2 remained fairly constant for all treatments and there was no observable trend with storage duration. The pH of formaldehyde treated colostrum remained above 4.8 for the 4 weeks of storage whereas that of the untreated control colostrum dropped to below pH 4.8 in the first 3 days and remained stable to the 4th week. This work has shown that inclusion of formaldehyde at levels as low as 0.05% (wt/vol.) preserves immunoglobulins of colostrum stored at high ambient temperature. The use of formic acid was not beneficial for preservation of colostral immunoglobulins. Thus colostrum preserved with formaldehyde may be of good feeding value for newborn calves whereas that preserved with formic acid may be useful only for older calves.     

Effects of Maternal Antibodies on Protection and Development of Antibody Responses to Human Rotavirus in Gnotobiotic Pigs

Although maternal antibodies can protect against infectious disease in infancy, they can also suppress active immune responses. The effects of circulating maternal antibodies, with and without colostrum and milk antibodies, on passive protection and active immunity to human rotavirus (HRV) were examined in gnotobiotic pigs. Pigs received intraperitoneal injections of high-titer serum (immune pigs [groups 1 and 2]) from immunized sows, low-titer serum from naturally infected sows (control pigs [groups 3 and 4]), or no serum (group 5). Immune or control colostrum and milk were added to the diet of groups 2 and 4, respectively. After inoculation (3 to 5 days of age) and challenge (postinoculation day [PID] 21) with virulent HRV, the effects of maternal antibodies on protection (from diarrhea and virus shedding), and on active antibody responses (measured by quantitation of antibody-secreting cells [ASC] in intestinal and systemic lymphoid tissues by ELISPOT) were evaluated. Groups 1 and 2 had significantly less diarrhea and virus shedding after inoculation but higher rates of diarrhea and virus shedding after challenge than did groups 3 and 5. Group 1 and 2 pigs had significantly fewer immunoglobulin A (IgA) ASC in intestinal tissues at PID 21 and at postchallenge day (PCD) 7 compared to group 5. Significantly fewer IgG ASC were present in the intestines of group 2 pigs at PID 21 and PCD 7 compared to group 5. There was a trend towards fewer ASC in intestinal tissues of group 2 than group 1, from PID 21 on, with significantly fewer IgA ASC at PCD 7. IgG ASC in the duodenum and mesenteric lymph nodes of group 3 and 4 pigs were significantly fewer than in group 5 at PCD 7. These decreases in ASC emphasize the role of passive antibodies in impairing induction of ASC rather than in merely suppressing the function of differentiated B cells. To be successful, vaccines intended for populations with high titers of maternal antibodies (infants in developing countries) may require higher titers of virus, multiple doses, or improved delivery systems, such as the use of microencapsulation or immune stimulating complexes, to overcome the suppressive effects of maternal antibodies.     

Oral infection of calves with Neospora caninum oocysts from dogs: humoral and cellular immune responses

Neospora caninum has been identified as a major cause of abortion in cattle in a number of countries throughout the world. Until the recent demonstration that dogs can serve as a definitive host of this parasite, it was not possible to study the infection in cattle orally exposed to oocysts. The aim of this study was to investigate the potential of N. caninum oocysts to infect calves, and to define initial immune responses that arise after oral infection. Seven calves were fed approximately 10(4)-10(5) N. caninum oocysts, three calves served as uninfected controls. Before infection, all calves were serologically negative for anti-Neospora antibodies and the calves were non-reactive to Neospora antigen in an in vitro lymphocyte proliferation assay. Peripheral blood lymphocytes from inoculated calves were able to mount in vitro proliferative responses to crude N. caninum antigen extract as early as 1 week p.i. Within 2 and 4 weeks p.i., Neospora-specific IgG1 and IgG2 antibodies were detected by IFAT and ELISA in serum from infected calves but not from sham-infected calves. The continued presence of reactive cells in the blood, spleen and mesenteric, inguinal, bronchial lymph nodes was seen as late as 2.5 months p.i., and parasite DNA was detected in the brain and spinal cord of the infected animals by PCR, indicating that the cattle were infected by oral inoculation of N. caninum oocysts collected from dogs, and that the animals were systematically sensitised by parasite antigen.     

The effect of colostrum period management on BW and immune system in lambs: from birth to weaning

The aim of this study was to investigate the BW and immune status of lambs reared under natural conditions or under artificial conditions fed two different colostrum amounts. In this study, 60 lambs were randomly divided into groups according to treatment. Twenty lambs remained with their dams (natural rearing (NR) group). Forty lambs were removed from their dams at birth. Lambs were bottle-fed with a pool of sheep colostrum, receiving either 4 g of IgG/kg of BW at birth (C4 group) or 8 g of IgG/kg of BW at birth (C8 group). The total colostrum amount was equally divided into three meals at 2, 14 and 24 h after birth. After this period, lambs were bottle-fed a commercial milk replacer. Blood plasma sample analysis and BW recordings were carried out before feeding at birth and then at 1, 2, 3, 4, 5 and 20 days after birth. Another blood sample analysis and BW recording was carried out when animals reached 10 kg of BW. During weaning (30 days), sampling was carried out every 5 days. Blood plasma was used to determine the concentrations of IgG and IgM and the complement system activity – total and alternative pathways. The NR group showed greater BW than the C4 and C8 groups during milk feeding period, whereas the C4 and C8 groups had greater BW than the NR group at the end of weaning period. The C8 and NR groups had greater plasma IgG and IgM concentrations than the C4 group during milk feeding period. In addition, C4 and C8 groups showed similar IgG concentrations and greater IgM concentrations than the NR group at the end of the weaning period. Complement system activity was greater in the NR group than in the C4 and C8 groups during the first 3 days after birth. In conclusion, lambs fed amounts of colostrum equivalent to 8 g of IgG/kg of BW showed similar immune variables compared to lambs reared under natural conditions, obtaining a greater BW at the end of the weaning period. Nevertheless, this study shows that not only the colostrum amount but also the management during the milk feeding and weaning period, such as stress produced by dam separation, milk quality and suckling frequency, can affect the final immune status of lambs.     

Pathogenicity of selected Toxoplasma gondii isolates in young pigs

The pathogenicity in 7-week-old pigs to five different Toxoplasma gondii strains of various host species origin was compared after i.v. inoculation of 10(4) tachyzoites. Additionally, one group of pigs was inoculated i.v. with 10(6) tachyzoites of the reference strain, SSI 119. In response to the infection a significant effect of T. gondii tachyzoite inoculation dose as well as differences among strains could be observed in several parameters. The 10(6)-dose inoculated pigs showed variable degrees of clinical illness and recurrent episodes of fever 4-17 days p.i., while pigs of four of the 10(4) tachyzoite inoculated groups experienced a short-lived rise in body temperature from day 6-8 p.i. without any apparent illness or inappetence. Control pigs and pigs infected with the least pathogenic strain had normal body temperature throughout the experiment. In all inoculated pigs, T. gondii-specific IgM and IgG antibodies appeared from day 8-10 and 10-17 p.i., respectively. Serum levels of alkaline phosphatase and the acute phase protein haptoglobin were decreased or increased, respectively, in response to the infection. Differential leukocyte count on peripheral blood revealed a significant lymphocytopenia on day 6 p.i. equal to both CD4+ and CD8+ T-cells, but shifting towards a reduced ratio of CD4+/CD8+ T-cells from day 8-14 p.i. In the 10(6)-dose inoculated pigs a considerable increase in zymosan induced and spontaneous oxidative burst capacity of peripheral blood leukocytes was observed from 6 days p.i. compared with control pigs. Oxidative burst capacity was not examined for other pigs. In conclusion, several useful parameters to identify differences in T. gondii pathogenicity other than mortality were identified. Furthermore, even at low doses, significant differences between recently collected Danish T. gondii field isolates were demonstrated after i.v. inoculation in young pigs.     

Protective effects of antibody against intestinal invasion by Escherichia coli

Seven Escherichia coli isolates from newborn calves with diarrhea were examined for enteropathogenic properties. One isolate penetrated into HeLa cells, four produced enterotoxin(s) and the remaining two possessed neither of these properties. Penetration of E. coli into HeLa cells was inhibited by antibody in bovine colostrum and in bovine and rabbit immune sera. The effective antibodies appeared to be mostly of the IgM class. The invasion by E. coli isolates was also examined by inoculation of the bacteria into the small intestine of E. coli-immunized and non-immunized guinea pigs. The isolate which penetrated into HeLa cells could penetrate the intestinal mucosa to be disseminated into various organs of non-immunized guinea pigs, but not of immunized guinea pigs, whereas no other isolates showed such pathogenicity in vivo. The inhibition of the invasion was observed when non-immunized guinea pigs were inoculated with the bacteria together with colostral or serum antibody. The results show the importance of antibody in the local defense mechanism against E. coli invasion.     

Human babesiosis in ireland: Further observations and the medical significance of this infection

Three splenectomized persons in Yugoslavia, California, and Ireland have been reported to be infected by three different Babesia species; two cases were fatal. In a study of the site where the fatal infection was contracted in Ireland, blood samples from 36 persons who had recently been bitten by ticks were inoculated into two splenectomized calves; no response to Babesia divergens was detected. Field-collected Ixodes ricinus ticks inoculated into another splenectomized calf resulted in fever and recovery of the agent of tick-borne fever (Cytoecetes phagocytophilia). This attempt to determine the presence of latent infection in human beings with intact spleens should be repeated on a larger scale in areas with a demonstrably high incidence of Babesia in ticks and animals. Few places in the world are free of piroplasms; their presence may present a hazard to splenectomized persons or to those whose splenic function is deficient.     

Antibody-Secreting Cell Responses and Protective Immunity Assessed in Gnotobiotic Pigs Inoculated Orally or Intramuscularly with Inactivated Human Rotavirus

Newborn gnotobiotic pigs were inoculated twice perorally (p.o.) (group 1) or intramuscularly (i.m.) (group 2) or three times i.m. (group 3) with inactivated Wa strain human rotavirus and challenged with virulent Wa human rotavirus 20 to 24 days later. To assess correlates of protection, antibody-secreting cells (ASC) were enumerated in intestinal and systemic lymphoid tissues from pigs in each group at selected postinoculation days (PID) or postchallenge days. Few virus-specific ASC were detected in any tissues of group 1 pigs prior to challenge. By comparison, groups 2 and 3 had significantly greater numbers of virus-specific immunoglobulin M (IgM) ASC in intestinal and splenic tissues at PID 8 and significantly greater numbers of virus-specific IgG ASC and IgG memory B cells in spleen and blood at challenge. However, as for group 1, few virus-specific IgA ASC or IgA memory B cells were detected in any tissues of group 2 and 3 pigs. Neither p.o. nor i.m. inoculation conferred significant protection against virulent Wa rotavirus challenge (0 to 6% protection rate), and all groups showed significant anamnestic virus-specific IgG and IgA ASC responses. Hence, high numbers of IgG ASC or memory IgG ASC in the systemic lymphoid tissues at the time of challenge did not correlate with protection. Further, our findings suggest that inactivated Wa human rotavirus administered either p.o. or parenterally is significantly less effective in inducing intestinal IgA ASC responses and conferring protective immunity than live Wa human rotavirus inoculated orally, as reported earlier (L. Yuan, L. A. Ward, B. I. Rosen, T. L. To, and L. J. Saif, J. Virol. 70:3075–3083, 1996). Thus, more efficient mucosal delivery systems and rotavirus vaccination strategies are needed to induce intestinal IgA ASC responses, identified previously as a correlate of protective immunity to rotavirus.     

Antigenic relationships between Candida albicans and various yeasts as reflected by immunoglobulin-class specificity.

A group of guinea pigs was inoculated into the foot pads with a single dose of Candida albicans in complete Freund's adjuvant, while another group was similarly inoculated once in the foot pads but also several times intramuscularly, with Candida alone. All guinea pigs were bled at different intervals after immunization and sera were separated chromatographically into IgG and IgM fractions. In order to study the antigenic relationships as reflected by immunoglobulin-class specificity, IgG and IgM fractions and whole sera obtained from guinea pigs differently immunized, were tested for the presence of agglutinins against C. albicans, six other species of Candida, and species of the ascosporogenous genera Saccharomyces, Kluyveromyces and Schizosaccharomyces. The results show that (1) only IgG fractions of the different sera prepared contained the specific anti-C. albicans antibodies; (2) IgG and IgM fractions of the sera obtained from a single inoculation did not reveal a specific pattern expressing antigenic relationships of the yeast studied, and (3) the IgM fractions of the sera obtained from several inoculations had a more homogenous pattern of reactivity, since mainly these contained the agglutinins against the ascosporogenous yeast species.