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D A Higgins

Publications and source records attributed to D A Higgins.

10 recordsLinked to original sources
PubMed1992

Structural relationship between the two IgY of the duck, Anas platyrhynchos: molecular genetic evidence.

cDNA clones encoding the H chains of the 7.8S and 5.7S IgY of the White Pekin duck have been isolated and sequenced. The H chain of the 7.8S IgY possesses four C region domains and thus resembles the H chain of chicken IgY with which it shows, in the C region, 54% inferred amino acid sequence identity, and complete conservation of the C region cysteine and tryptophan residues. The H chain of the 5.7S IgY possesses only two C region domains, that are virtually identical to CH1 and CH2 of the 7.8S IgY H chain. Although Southern blot genomic analysis did not resolve whether the two transcripts encoding the H chains of the 7.8S and 5.7S IgY are derived from one or two H chain-encoding genes, the CH 1, 2, 3, and 4 exons are apparently colinear, and no evidence was found for a separate locus in which CH1 and 2 exons were present and CH3 and 4 exons were lacking. The VH domain-encoding sequences of the cDNA for the two IgY H chains showed high similarity in the inferred VH gene (93% nucleotide and 91% inferred amino acid identity) and in the inferred JH segment (89% nucleotide and 93% inferred amino acid identity) but low similarity in the D region (26% nucleotide and 7% inferred amino acid identity). Genomic Southern blot hybridization analysis showed multiple VH-hybridizing sequences represented on up to 20 restriction fragments.

Amino Acid Sequence↗
PubMed1992

Duck lymphocytes. VI. Requirement for phagocytic and adherent cells in lymphocyte transformation.

Preparations of duck (Anas platyrhynchos) spleen and blood lymphocytes depleted of cells capable of phagocytosing carbonyl iron gave lower transformation responses to the mitogens phytohaemagglutinin (PHA), concanavalin A (Con A), Bandeiraea simplicifolia seed lectin (BSS), wheat germ agglutinin (WGA), lentil lectin (LL) and phorbol ester (PMA) than intact cell preparations. When cell populations were fractionated on the basis of their adherence to plastic, it was found that the adherent cells were responsive to PHA, Con A, BSS, WGA and PMA, while the non-adherent cells responded to LL. These observations confirm the expected requirement for phagocytic accessory cells in the induction of in vitro mitogen-driven duck lymphocyte responses. The responses of plastic-adherent populations of cells to most mitogens are believed to reflect the generally close physical relationship between the adherent accessory cells and the lymphocytes, although it remains possible that duck monocytes respond to some of the mitogens employed. The data also suggest that LL stimulates a population of cells different to those responding to other mitogens.

Animals↗
PubMed1992

Duck lymphocytes--V. Transformation responses to phorbol ester and calcium ionophore.

1. Lymphocytes purified from duck blood and spleen were cultured in the presence of phorbol 12-myristate 13-acetate (PMA) and the calcium ionophore A23187. Stimulation was assessed by the incorporation of [3H]thymidine after 3 days' culture. 2. PMA stimulated over a wide range of concentrations, with maximum stimulation at final concentrations of 5 x 10(-7)-5 x 10(-8) M/litre. A23187 was effective in the range 5 x 10(-6)-5 x 10(-7) M/litre and also, in some experiments using spleen lymphocytes, at 5 x 10(-11)-5 x 10(-12) M/litre. 3. Synergism was observed between PMA and A23187, the pattern depending on the concentrations of these reagents employed. Synergism was also observed between PMA and suboptimum concentrations of phytohaemagglutinin (PHA), wheat germ agglutinin (WGA), pokeweed mitogen (PWM) and Bandeiraea simplicifolia seed extract (BSS), but not with concanavalin A (Con A), lentil lectin (LL) or Helix pomatia lectin (HP). Similarly, synergism occurred between A23187 and WGA or PWM, but not with PHA, BSS, Con A, LL or HP. 4. Mitomycin C and cycloheximide inhibited the response of duck lymphocytes to PMA, A23187 and lectins. Cyclosporin A inhibited responses to lectins but not to PMA or A23187. Neither hydrocortisone nor indomethacin inhibited responses to lectins, PMA or A23187. 5. These results indicate that activation of duck lymphocytes occurs by virtue of similar intracellular messenger pathways to those operating in mammalian lymphocytes.

Animals↗
PubMed1977

Bovine lymphocytes: enhanced E-rosette formation after storage or gradient centrifugation.

Incubation of bovine thymus lymphocytes with SRBCs for 1 hr or more at 0 degrees C during the E-rosette test gave higher rosette counts than tests receiving no such incubation. Further enhancement was seen if lymphocytes were stored in foetal calf serum (FCS) or BSA solutions at 4 degrees C for 18 hr prior to rosette tests. Best enhancement due to storage in BSA was seen when cells were subsequently tested in FCS. However, after storage in BSA many rosettes occurred when tests were done in BSA, Albeit few rosettes occurred in BSA without prior storage. Less enhancement was seen after storage in sodium metrizoate (NaM). Enhancement in FCS and 10% BSA occurred after 1 day, but not 2 or more days, of storage at 4 degrees C, but was not seen when cells were stored at 37 degrees C. Rosette formation was about doubled by centrifugation of lymphocytes through BSA gradients prior to rosette tests; centrifugation through NaM gradients had no such effect. It is suggested that rosette formation is a property of an immature bovine T cell, and that on storage some cells develop and subsequently lose the ability to form rosettes.

Animals↗
PubMed1977

Bovine lymphocytes: recognition of cells forming spontaneous (E) rosettes.

About 20% of thymus lymphocytes from neonatal calves formed spontaneous (E) rosettes with SRBCs in medium consisting of 50-100% foetal calf serum (FCS); other media were less satisfactory. FCS was necessary both to allow rosette formation to occur and to maintain stability of the rosettes once formed. Rosettes were stable at 0 degrees C but unstable at 18 degrees C and 37 degrees C. Dead thymus cell (sodium azide treated) did not form rosettes. Treatment of thymus cells with antiserum to bovine Ig-inhibited rosette formation, but this inhibition was considered non-specific since it also occurred with normal rabbit serum. Treatment of SRBCs with neuraminidase slightly enhanced rosette formation by thymus cells, but did not induce peripheral blood lymphocytes to form rosettes. Rosette formation did not occur under a variety of conditions with normal or neuraminidase-treated human, horse, pig, rabbit, guinea-pig, chicken or autologous RBCs. SRBC rosette forming cells were also found in lymph nodes (2-14%) and spleen (less than 5%), but rarely or never in peripheral blood and bone marrow of calves and adults. In foetuses at 80 days of gestation, 49% of thymus cells formed E rosettes. Foetal lymph node cells formed E rosettes at 160 days and spleen at 180 days. Cells with membrane-bound Ig were observed by IFT; their distribution did not coincide with the occurrence of E rosettes. E-rosette formation might be a marker for a subpopulation of bovine T cells.

Animals↗
PubMed1976

Some effects of silical treatment on Marek's disease.

Treatment of newly hatched chicks with silica by the intraperitoneal route delayed the onset of mortalities due to the JM strain of Marek's disease (MD' virus inoculated at 6 days of age. During the 88-day observation period fewer silica-treated chicks died of MD, but this difference was not usually statistically significant. Silica treatment had no effect on the susceptibility of 4-week-old birds. Silica treatment reduced the antibody response to MD but, in general, not significantly. The antibody response to bovine serum albumin was significantly enhanced if measured by the indirect hemagglutination test but not if measured by the agar gel diffusion test, whereas the response to Brucella abortus was enhanced significantly in N-line (MD-resistant) chicks but not significantly in P-line (MD-susceptible) chicks. Five days after infection, silica-treated chicks had significantly less fluorescing antigen in thymus and bursa than did untreated chicks; no difference was observed in the spleen. After silica treatment the glass-adherent cell population in the buffy coat was increased by up to 10-fold compared with untreated chicks. It is suggested that silica treatment induced macrophage proliferation, with subsequent restriction of MD virus spread, yet allowed an adjuvant-type effect with other antigens.

Animals↗
PubMed1976

Fractionation of fowl immunoglobulins.

Serum, Na2SO4-precipitated serum immunoglobulins and bile from 12-week-old fowls, and serum from day-old chicks, were fractionated by Sephadex G-200 gel filtration, DEAE Sephadex A-50 ion exchange chromatography and ultracentrifugation through 10-40 per cent sucrose gradients. Elution of IgM, IgG, IgA and albumin was monitored by examination of fractions in agar gel diffusion against antisera specific to these proteins. Serum and bile from 12-week-old fowls contained IgM and IgA in two molecular sizes and a single molecular size of IgG. Day-old chick serum contained IgM estimated to be 7S, a polymerised form of IgG in addition to the normal 7S component, and a small molecular weight protein antigenically related to IgA. Most of the albumin in bile was of lower molecular weight than serum albumin, while heavy forms of albumin were detected in ultracentrifugation of bile and day-old chick serum.

Animals↗
PubMed1975

Fowl immunoglobulins: quantitation and antibody activity during Marek's disease in genetically resistant and susceptible birds.

Five-week-old birds of resistant (N) and susceptible (P) genetic lines were inoculated with the JM strain of Marek's disease (MD) virus. MD occurred only in P-line birds; one-third had died by the end of the experiment (63 days after inoculation). Sera were examined for antibodies (precipitating, virus neutralizing,and fluorescing), and immunoglobulins were measured. Antibodies were associated with immunoglobulin classes by density gradient centrifugation and utilization of specific antisera to gowl immunoglobulins in indirect immunofluorescence. Precipitating antibodies were found in both lines; they first appeared 7 days after inoculation in P-line birds and 14 days after inoculation in N-line birds, but thereafter there was no difference between the two genetic lines. A peak of neutralizing antibody occurred in both lines between 6 and 12 days. Thereafter neutralizing antibodies increased gradually throughout the experiment. Neutralizing antibody levels were at this stage often higher in N-line than in P-line birds. The fluorescent antibody test showed transient immunoglobulin (Ig) M antibody from 7 to 9 days in N-line birds and 5 to 12 days in P-line birds; this corresponded with the initial peak of neutralizing antibody. Antibodies were seen from 7 to 8 days after inoculation and increased gradually durin gthe experiment, generally paralleling the secondary increase in neutralizing antibodies. Ultracentrifugation confirmed the presence of IgM and IgG antibodies as described. Antibodies of the IgA class were not found. The alterations in serum immunoglobulin levels occurred in three phrases: (i) 1 to 9 days postinfection, there was an increase in IgM and IgA compared with uninfected control birds; (ii) 10 to 20 days postinfection, Ig M and IgA levels were lower than in control birds; and (iii) 21 days postinfection, until the end of experiment, IgA returned to normal levels, IgG increased to about eight times higher than in control birds, and IgM in P-line birds returned to normal levels and in N-line birds reached and maintained levels about double those of control birds. Another experiment was designed to examine the separate effects of moving and inoculation of uninfected kidney cells and virus-infected kidney cells. The changes in immunoglobulins observed in the first experiment occurred only after infection with MD virus and were not related to movement or handling stress. It was concluded that no significant primary difference exists in the humoral immune system between fowls resistant and susceptible to MD; all differences could be related to the immunosuppressive effects of MD, which are greater in susceptible birds apparently due to the greater lymphoid tissue damage in these strains.

Animals↗
PubMedDate not supplied

Rous sarcoma regression in chickens resistant or susceptible to Marek's disease.

In 4 experiments, strains of chickens relatively susceptible (S-strain, P-line) or resistant (N-line, PDRC) to Marek's disease (MD) were challenged with Rous sarcoma virus (RSV) at 6-8 weeks old. RSV tumors occurred in 94-100% of the birds in each strain, but the number with tumors that regressed during the 40-46-day experiment varied from 7% (S-strain) to 91% (PDRC). The N-line and P-line birds, derived from a random-bred flock with selection only for susceptibility or resistance to MD, regressed their tumors at about equal rates (respectively 59 and 65%). Thus, although the genetic strains differed in ability to regress RSV tumors, the difference was not necessarily related to genetic resistance or susceptibility to MD. Other birds in 2 of the experiments, infected 2-4 weeks earlier with JM or GA isolants of MD virus, had significantly (P less than 0.01) lower incidence of RSV tumor regression than did controls provided that they developed gross lesions of MD.

Animals↗