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Biomedical subjects

H M Dockrell

Publications and source records attributed to H M Dockrell.

63 records · Page 4Linked to original sources
PubMed1981

Endotoxin-induced serum factor kills malarial parasites in vitro.

We investigated the possibility that malarial parasites may be killed by nonspecific soluble mediators, such as those in tumor necrosis serum, that are obtained from mice given macrophage-activating agents like Corynebacterium parvum or Mycobacterium bovis BCG, followed by endotoxin. Such sera killed parasites in vitro after overnight incubation; killing was measured directly by using an in vivo infectivity assay. Parasite infectivity was not decreased by incubation in sera from mice given C. parvum or BCG alone (no endotoxin) or by incubation in sera from normal mice given endotoxin. Plasmodium yoelii, its lethal variant, and Plasmodium berghei were equally susceptible to inactivation. Sera obtained from mice given endotoxin during the course of infection with these parasites also contained parasite-killing factor. The activity of this factor appeared to be proportional to parasitemia in that it was higher in the sera from mice infected with the lethal parasites than in the sera from mice with infections which resolved either spontaneously or after vaccination.

Animals↗
PubMed1980

The role of the liver in immunity to blood-stage murine malaria.

Mice vaccinated with fixed parasitized red blood cells and Bordetella pertussis can clear an otherwise lethal Plasmodium yoelii infection in 7 days; this protection is abolished by splenectomy before vaccination. Most mice splenectomized following vaccination were able to clear their infections, although their recovery was delayed. When labelled parasitized red cells were injected into mice during an infection, splenic uptake fell from day 3 onwards while uptake by the liver increased. Lymphocytes (mainly T cells) formed the majority of the live cells extracted from livers 7 days after infection, although blasts and myeloid cells were also present. Infected livers from vaccinated mice contained most cells. Less marked increases were observed 7 days after P. berghei infection of vaccinated mice. Examination of liver tissue showed that the sinusoids contained increased numbers of cells and suggested that activation of Kupffer cells was occurring, particularly in vaccinated mice infected with P. yoelii. Homing experiments confirmed the increased trapping of various cells in livers of vaccinated mice infected with P. yoelii. These results suggest an important role for the liver in recovery from blood-stage malaria infection.

Animals↗
PubMed1979

Cell-mediated immunity in the liver of mice vaccinated against malaria.

Mice can be protected against several species of lethal malaria infection by vaccination, and their recovery correlates well with increased anti-malarial antibody levels, particularly IgG (ref.2). However, there is also a good correlation between protection by vaccines and priming for delayed-type hypersensitivity in the skin, although there is no obvious explanation for this effect. We now report an apparent relationship between protection and a cell-mediated immune response involving the migration of various types of cell capable of killing malaria parasites in vitro to the liver. We suggest that the effect of vaccination is to bring together parasites, specific antibody and nonspecific cytotoxic cells, and that the liver may be a major site for their interaction.

Animals↗
PubMed1979

Histochemical identification of T cells in oral lichen planus.

Lysosomal activity was demonstrated in the majority of the lymphocytes forming the mononuclear cell infiltrate in oral lichen planus. Staining for acid phosphatase, N-acetyl-beta-D-glucosaminidase, nonspecific esterase, and beta-glucuronidase was present in these cells in tissue sections, indicating their T cell origin. Small numbers of enzyme-negative lymphocytes were also present. Macrophages showing stronger staining were found scattered through the infiltrates in large numbers. These observations indicate roles for T cells and macrophages in the pathogenesis of lichen planus.

Acetylglucosaminidase↗
PubMed1978

Enzyme differentiation of lymphocyte subpopulations in sections of human lymph nodes, tonsils and periodontal disease.

Five enzymes have been studied to differentiate between T and B lymphocytes in sections of human lymph nodes, tonsils and chronic inflammatory periodontal disease. The presence of acid phosphatase, beta-glucuronidase N-acetyl-beta-glucosaminidase, non-specific esterase and fluoride-resistant esterase activity was determined histochemically. The results indicate that cells in the B area of both lymph nodes and tonsils are negative for enzyme activity, while those in the T area show a single intense granule of activity. These enzymes were unable to differentiate between T blasts, B blasts and plasma cells in the sections studied. The majority of the lymphoid cells in the lesions of chronic inflammatory periodontal disease are enzyme-negative and probably of B-cell origin.

B-Lymphocytes↗
PubMedDate not supplied

Detection of high titres of Toxoplasma gondii antibodies in sera of patients with leprosy in Pakistan.

Untreated and treated leprosy patients and their household contacts were screened for antibody to Toxoplasma gondii using antigen-coated latex particles. A significantly high level of seroprevalence (29.6%) was observed in the untreated leprosy patients compared to endemic controls (P < 0.01) with a mean reciprocal antibody titre of 20,007 +/- 3580 (n = 98) in seropositive patients. In treated patients seroprevalence dropped to 13.5%. Seroprevalence in a group of household contacts of leprosy patients was similar to that of control subjects from an endemic area but not exposed to leprosy (7.8% and 6.1% respectively), indicating that the increased seroprevalence in leprosy patients was not merely due to increased exposure related to socioeconomic factors. Antigenic cross-reactivity between T. gondii and Mycobacterium leprae antigens was ruled out by cross inhibition experiments carried out with soluble antigens from each of the organisms. We believe these antibodies may be induced by an increase in T. gondii load in leprosy due to a transient reactivation of latent T. gondii infections, as the antibodies in these leprosy patients were not associated with any sign of eye or lymphatic pathology related to toxoplasmosis.

Adult↗
PubMedDate not supplied

Blood-stage malaria in Biozzi high and low antibody responder mice: the importance of antibody and macrophages in immunity.

Mice from Biozzi high (H) and low (L) antibody responder lines were infected either with non-lethal Plasmodium yoelii 17X, with a lethal variant of the same parasite or with P. chabaudi (non-lethal). H mice recovered from infection with both P. yoelii and its normally lethal variant, whereas L mice died from both. However, L mice showed better initial control of parasitaemia with all three infections. Both H and L mice infected with P. chabaudi showed a similar rapid reduction of parasitaemia once it had reached 40-50%, but L mice were unable to clear the infection completely. When infected with either non-lethal P. yoelii or P. chabaudi, H mice made substantially more antibody than L mice, especially around the time of recovery. The courses of parasitaemia suggest a role for non-antibody factors in early control of infection and for antibody in recovery from P. yoelii. Although antibody was apparently necessary for complete recovery from P. chabaudi, the first rapid fall in parasitaemia appeared to be unrelated to antibody levels.

Animals↗
PubMedDate not supplied

Cytochemical identification of T and B cells in situ in mouse lymphoid tissue and lymph nodes from the rat, gerbil and cat.

The use of enzymes as markers of T or B cells in tissue sections has been studied in mouse lymphoid tissue and lymph nodes from the gerbil, rat and cat. Lymphocytes in the T-cell areas of murine lymph nodes and spleen contained discrete dots of non-specific esterase and N-acetyl-beta-D-glucosaminidase (beta-glucosaminidase) activity, with weak acid phosphatase activity. Lymphocytes in the B-cell areas lacked this discrete staining. Cortical thymocytes contained slight esterase activity while medullary thymocytes were strongly positive for both esterase and beta-glucosaminidase. Lymphocytes with a T-cell staining pattern were only occasionally seen in lymph nodes from Nude (nu/nu) mice. ATPase staining was restricted to lymphocytes in the B-cell areas; weak 5'-nucleotidase staining was only present in a frew lymphocytes in both T- and B-cell areas. Blast cells stimulated by in vivo injection of ConA or PHA in the mouse showed strong discrete enzyme activity for non-specific esterase and beta-glucosaminidase. Lipopolysaccharide-stimulated blast cells and cells within germinal centres lacked this discrete staining. Comparison of lymph nodes from the gerbil, rat and cat suggested at least on enzymes as a T-cell marker in each species although considerable variation in staining profiles was seen in the different species.

Acid Phosphatase↗