Recombinant human interleukin-2 (rhIL-2) was evaluated for its influence on total and differential WBC counts lymphocyte blastogenic responsiveness to mitogens, and several measurements of neutrophil function in clinically normal and in dexamethasone-treated cattle. A single dose of rhIL-2 (2.5 X 10(7) U) given SC had no influence on the total or differential WBC count; however, it did cause an inhibition of neutrophil random migration. The other measurements of neutrophil function (Staphylococcus aureus ingestion, cytochrome C reduction, iodination, and antibody-dependent and antibody-independent cell-mediated cytotoxicity) evaluated were not significantly altered. The rhIL-2 treatment was associated with a significant (P < 0.01) decrease in uptake of [3H]thymidine in unstimulated lymphocytes and a tendency toward enhanced blastogenesis of lymphocytes stimulated with phytohemagglutinin. This enhancement was significant (P < 0.05) only when the results were expressed as a stimulation index. Lymphocyte responsiveness to concanavalin A and pokeweed mitogen was not significantly influenced by rhIL-2 administration. Dexamethasone (0.04 mg/kg) administered every 24 hours for 3 consecutive days altered the WBC count and several measurements of lymphocyte and neutrophil function. The administration of a single dose of rhIL-2 (2.5 x 10(7) U) 8 hours after the first dose of dexamethasone did not alter the influence of dexamethasone on any of the measurements. These results indicated that rhIL-2 has some biologic activity in cattle, but when used as administered here, did not overcome the influence of dexamethasone on the in vitro measurements of lymphocyte and neutrophil function that were evaluated.

Immunosuppressed rats inoculated with Cryptosporidium oocysts isolated from calves' feces were treated with arprinocid, 50 mg/kg of body weight/d. As determined from differences in the mean number of cryptosporidial developmental stages per villus in treated vs control rats, arprinocid had a substantial effect on cryptosporidial activity, which was parasitistatic instead of parasiticidal. Drug-ranging experiments indicated that arprinocid was effective at 50 and 25 mg/kg/d, but not at 12.5 mg/kg/d. These results suggest that further testing of arprinocid in different animal models, or in phase-I clinical trials, is warranted.

The clinicopathologic manifestations of bovid herpesvirus-4 (BHV-4; FCAHV strain)-induced infection of the lower portion of the urinary tract were characterized in 12 adult neutered male and 6 female specific-pathogen-free cats, and were compared with those in 12 neutered male control cats. Six neutered male and 6 female cats were given immunosuppressive doses of methylprednisolone acetate prior to inoculation of their urinary bladders with BHV-4. Six neutered male control cats were given immunosuppressive doses of methylprednisolone acetate prior to inoculation of their urinary bladders with uninfected tissue culture control inoculum. Six additional neutered male control cats were exposed only to uninfected tissue culture control inoculum. All cats were observed for 90 days following inoculation. Dysuria and gross hematuria were observed in only 1 BHV-4-exposed cat. Radiographic abnormalities of the lower portion of the urinary tract were not observed. Microscopic hematuria, crystalluria, and lipiduria were identified with similar frequency in BHV-4-exposed and control cats. Results of urine culturing for bacteria, mycoplasma, ureaplasma, and viruses were negative. Viruses were not isolated from blood leukocytes collected from exposed or control cats. Three to 6 weeks after inoculation, high concentrations of BHV-serum 4 antibodies were detected in all exposed cats by an indirect fluorescent antibody test. Light microscopic examination of the urinary tract revealed multifocal lymphoid cystitis in 2 BHV-4-exposed cats. Except for suppurative bronchitis in 1 BHV-4-exposed cat given glucocorticoids, morphologic differences in urinary and extraurinary tissues were not observed. In urinary bladder tissue collected 90 days after inoculation, BHV-4 was reisolated from urinary bladder explants of all but 1 exposed cat. Virus was also isolated from a kidney explant of 1 exposed male cat, and spleen cell cocultures of 1 exposed female cat given glucocorticoids. Bovid herpesvirus-4 (FCAHV strain) caused persistent urinary tract infections in male and female specific-pathogen-free cats. Detection of occult BHV-4 infection required isolation of virus from tissues by explantation, or demonstration of specific BHV-4 antibodies by immunofluorescent fluorescent techniques. Administration of glucocorticoids prior to inoculation did not enhance morbidity associated with BHV-4 urinary tract infection. Further investigations are needed to determine the pathogenic role of BHV-4 in 4 noninduced feline lower urinary tract disease.

Fifty-four neonatal pigs were allotted to 4 groups and reared in an electrically controlled automatic feeding device (autosow). Each group was reared on a different pool of bovine colostrum: fresh, stored 1 month, stored 6 months, and stored 8 years. Bovine and porcine immunoglobulins in the sera of these pigs, and in a group of conventionally reared pigs, were measured periodically during the first 42 days after birth. The maximal concentration of absorbed bovine immunoglobulin was reached between 12 and 18 hours and equaled or exceeded the amount of porcine immunoglobulin absorbed by the conventionally reared pigs. Large differences in the concentrations of the bovine immunoglobulin isotypes among the various pools of colostrum were positively correlated with concentration of these isotypes in the sera of the neonatal pigs fed these pools. Relative to their concentrations in colostrum, approximately 41% of the IgG1, 55% of the IgG2, 29% of the IgM, and 67% of the IgA was absorbed. The IgA was absorbed the best and IgM was least absorbed. Significant trends or differences in absorption were not observed among groups. Neonatal pigs given fresh colostrum, which had a higher fat content, had significantly more weight gain (P < 0.05). This occurred, despite the fact that the fresh colostrum had the lowest concentration of bovine immunoglobulin. Serum half-lives for bovine IgG1 and IgG2 were significantly less than for porcine IgG (P < 0.05), whereas the half-lives for bovine and porcine IgM and IgA were similar. De novo-synthesized immunoglobulins were detectable in serum after 6 days; IgM concentrations reached a maximum at 15 days in neonatal pigs given stored, but not fresh, colostrum. The IgG and IgA concentrations steadily increased in all groups and were highest on day 42, when the study was terminated. Neonatal pigs ingesting fresh colostrum had significantly lower concentrations of de novo-synthesized IgG and IgA than pigs fed stored colostrum (P < 0.05). Concentrations in these pigs were also lower than those in conventionally reared pigs. This occurred, despite the lower immunoglobulin concentration in fresh colostrum, and correspondingly, the lower amount of bovine immunoglobulin in pigs that received this colostrum and absorbed it into their serum. In most instances, the amounts of immunoglobulin of any isotype absorbed from stored colostrum and the amount of de novo-synthesized immunoglobulin present 6 weeks later, were inversely correlated. Data indicated that a storage-labile, nonimmunoglobulin factor, in bovine colostrum is able to suppress de novo IgG and IgA synthesis by neonatal pigs.

Eighteen female lambs with prior exposure to Haemonchus contortus infections were ovariectomized and assigned to 1 of 3 replacement regimens: 0, 25, or 250 mg of progesterone/d delivered IM. After 3 weeks of hormonal treatment, all lambs were inoculated with 100,000 infective larvae of H. contortus. After 8 weeks of hormonal treatment, a blastogenic assay was performed on blood lymphocyte populations, and the abomasum from each lamb was obtained for larval and adult worm recoveries of H. contortus. Lambs of the 25 mg of progesterone group had significantly (P < 0.05) reduced blastogenic response to concanavalin A and greater adult and larval populations, compared with controls. Lambs of the 250 mg of progesterone group had worm burdens and lymphocyte blastogenesis values intermediate between those of the other treatment groups.

Bone marrow fibroblast colony-forming units (CFU-F) were evaluated in cats experimentally infected with different isolates of FeLV. Cats infected with the Kawakami-Theilen isolate of FeLV (FeLV-KT) had progressive decrease in the number of CFU-F at 2, 4, and 6 weeks after infection. The number of CFU-F in FeLV-KT-infected cats ranged from 38 to 70% of the preinoculation CFU-F value. Of 3 cats with FeLV-KT-induced suppression of CFU-F, 2 developed fatal nonregenerative anemia. Cats infected with the Rickard isolate of FeLV (FeLV-R) had more moderate decrease in the number of CFU-F at 2, 4, and 6 weeks after infection. The number of CFU-F in FeLV-R-infected cats ranged from 62 to 82% of the preinoculation CFU-F value. The FeLV-R-infected cats did not become anemic.

Immunodeficiency in neonatal and young pigs was studied in terms of T-cell function. Generalized T-cell deficiency did not exist in young pigs on the basis of the in vitro response of blood mononuclear cells to a polyclonal T-cell mitogen, phytohemmagglutinin. However, immunodeficiency that extended from birth up to 4 weeks, was observed in serum antibody concentration and in vitro proliferative responses of blood mononuclear cells from young pigs exposed to a low antigen dose of a T-cell dependent antigen, egg white lysozyme. The low in vitro proliferative response to lysozyme was not attributable simply to a lack of interleukin-2 production, because supplementation with human interleukin-2 did not enhance the in vitro cellular response. Also, pokeweed mitogen-stimulated B cells from young pigs up to the age of 5 to 6 weeks produced immunoglobulin concentration, which also was not affected by the addition of human interleukin-2 to the in vitro cultures. The blood mononuclear cells obtained from pigs within the first 5 to 6 weeks after birth and incubated with monoclonal antibodies reactive to all T cells (MSA4), helper T cells (74-12-4) or suppressor/cytotoxic T cells (76-2-11) did not yield consistent excess of suppressor/cytotoxic T cells. This observed immunodeficiency cannot be attributed to a simple lack of functional T cells or to an excessive number of suppressor/cytotoxic T cells, but may be a property of the ability of specific T-cell clones to respond t o low concentration of T cell-dependent antigens or may be attributable to the induction of a suppressor T-cell population in response to in vitro stimulation with the polyclonal T-cell-dependent pokeweed mitogen system.