Distribution of T and B cells in thymus, blood and lymph nodes of the cat.

The proportions of T and B cells in the thymus, blood and lymph nodes were estimated in cats from three months to three years of age. T cells were identified by formation of E rosettes with guinea-pig red blood cells and B cells by the presence of surface immunoglobulin (Ig) as shown by the mixed antiglobulin reaction. Using a double test, it was shown that these methods identify separate, non-overlapping cell populations. The proportions of T cells shown in the thymus ranged from 10-73 per cent, in the blood 5-62 per cent and in the nodes, 5-44 per cent. Cells with surface Ig ranged from 0-10 per cent in the thymus, 26-68 per cent in the blood and 32-18 per cent in the nodes. Two cats with lymphadenopathy had unusually high B cell counts and one cat with depletion of the thymus was deficient in peripheral T cells. Papain treatment reduced or abolished E rosette formation by T cells.

Monocytic leukaemia in the dog.

Three cases of monocytic leukaemia in dogs are reported. Clinically, they all showed dullness, lymph node enlargement and hepato-spenomegaly and the overt illness was of short duration. Haematologically, the white blood cell count was raised to different degrees in each case. The great majority of white cells were monocytes and monoblasts; their cytological, cytochemical and electron microscopic features are described. Only a mild degree of anaemia was present in all cases. Pathological examinations, carried out in two of the dogs, showed widespread leukaemic infiltration of bone marrow, spleen, lymph nodes, liver and other organs. Differentiation of this syndrome from other forms of haemopoietic neoplasia is discussed.

Visual dominance in the cross-modal kinesthetic to kinesthetic plus visual feedback condition.

In previous studies subjects who have learned a positioning response with kinesthetic feedback tended to make greater errors when visual feedback was provided during later trials. These subjects have always performed with both kinesthetic and visual feedback available. This study determined whether subjects with only visual feedback would produce errors similar to those who received kinesthetic plus visual feedback. Blindfolded subjects learned to move a handle to a criterion location with knowledge of results following each trial. Subjects then were assigned to one of three experimental groups, with only kinesthetic feedback, with kinesthetic plus visual feedback, or with only visual feedback. Subjects had 9 trials without knowledge of results in these feedback conditions. When visual feedback was available, subjects tended to make longer response errors. This finding replicates previous studies. Also, the similarity of performances from the conditions with visual feedback indicated the dominance of visual information in the condition with kinesthetic plus visual feedback.

Neoplastic diseases of the haematopoietic and lymphoid tissues.

Systemic lymphosarcomas are common in all species of domestic mammal. A binomial classification of these tumours, based on both the anatomical form (i.e., distribution of lesions) and the type of cytology, is proposed. Mast cell tumours also are common, especially in the dog. The categories of lymphoid neoplasms described are: lymphosarcoma, lymphoid leukaemia, nodular lymphoid hyperplasia, tumours of the immunoglobulin-forming cells, and thymoma. The myeloid neoplasms described are: myeloid leukaemia, erythroleukaemia, acute erythraemia, polycythaemia vera, megakaryocytoid leukaemia, panmyelosis, myelosclerosis, and monocytoid leukaemia. Mast cell tumours are divided into mastocytoma and malignant mastocytosis.

Tumours of the liver and biliary system.

In this histological classification of liver and gall bladder tumours the tumour types largely correspond to those found in man. The most common tumours in this group are liver cell adenoma, hepatocellular carcinoma, and cholangiocarcinoma.

Tumors of the kidney.

The most frequent renal tumours of animals are renal cell carcinoma and nephroblastoma. Renal cell carcinomas are seen mainly in dogs and cattle and nephroblastoma is encountered in pigs, puppies, and calves. Renal cell carcinomas are usually papillary in the dog. They show a marked propensity for vascular invasion, penetration of the posterior vena cava, and subsequent pulmonary metastasis. Nephroblastoma, which is morphologically identical to Wilms' tumour of children, is almost always a benign tumour in animals. It is one of the most frequent neoplasms of pigs, possibly owing to the fact that most pigs are slaughtered (and examined) when a few months old. Lymphosarcoma involving the kidney is particularly frequent in the cat, but is also seen in other species as part of a generalized disease.

Virulent P. berghei malaria: prolonged survival and decreased cerebral pathology in cell-dependent nude mice.

The course of lethal Plasmodium berghei infection was examined in nu/+ and T cell-deficient nu/nu BALB/c mice. A rapidly fatal neurologic syndrome, including ataxia, hemiparesis, and seizures, was seen in the nu/+ mice early in the infection, whereas this syndrome was absent in the nu/nu mice. The nu/nu mice also developed anemia more slowly, had lower levels of immune complexes and total IgG, and had smaller decreases in serum C3 compared with the nu/+ mice. Histopathologic examination of the brains revealed cerebral malaria lesions, including vascular plugging and micro-hemorrhages, in the nu/+ mice but not in the nu/nu mice. Cerebral lesions similar in frequency and severity to those in nu/+ mice developed in nu/nu mice given spleen cells from normal nu/+ mice. The results suggest that an intact immune system is necessary for the expression of cerebral malaria.

Immunopathological aspects of Plasmodium berghei infection in five strains of mice. II. Immunopathology of cerebral and other tissue lesions during the infection.

Histological changes during the course of P. berghei infection were investigated in A/J, BALB/c, OF1, CBA and C57B1 mice. The findings were studied in relation to serological aspects (Contreras et al., 1980). High mortality and acute deaths occurred in A/J, BALB/c and OF1 mice and marked cerebral lesions were found in these strains from day 15, including congestion of meningeal and cerebral veins and capillaries, blocking of these vessels by heavily parasitized RBC, cerebral oedema and haemorrhages. Such lesions were minimal in CBA and C57B1 mice, and absent in mice examined 21 and 24 days after infection. Small deposits of IgG and traces of C3 were detected by immunofluorescence in the choroid plexus of most mice from day 9. Renal lesions included congestion, plugging of veins and capillaries, low-grade mononuclear infiltration and mesangial thickening; these changes were most marked in CBA, C57B1 and A/J mice. Glomerular deposits of IgM were present in all strains in the first week of infection. IgG and C3 were detected in the second week, but only traces were found in CBA mice. The livers showed congestion, accumulation of pigment in swollen Kupffer cells and mononuclear portal infiltration; these were most pronounced in A/J mice. In the spleen, there was a great increase in the reticuloendothelial cell population, white pulp proliferation, congestion and accumulation of pigment and plasma cell reaction; the pattern of white pulp expansion varied in the different strains. The results suggest that cerebral lesions play a significant role in the aetiology of acute deaths in this malaria model.

Diagnosis of Plasmodium falciparum infection in man: detection of parasite antigens by ELISA.

An ELISA method has been developed for the diagnosis of Plasmodium falciparum infection in man. Parasites from in vitro cultures of P. falciparum were used as source of antigen for the solid phase and the source of specific antibody was immune Gambian sera; binding of antibody in antigen-coated wells was registered by means of alkaline phosphatase-conjugated anti-human IgG. Parasites were detected on the basis of inhibition of antibody-binding. The test was applied to the detection of parasites in human red blood cells (RBC) from in vitro cultures of P. falciparum and in RBC from infected Gambians; RBC from 100 Geneva blood donors served as normal, uninfected controls. In titration experiments, the degree of antibody-binding inhibition correlated with the number of parasites in the test RBC. Parasites were detected at a level of 8 parasites/10(6) RBC. Samples of RBC were tested from 126 Gambians with microscopically proven infection; significant antibody-binding inhibition was found in 86% of these cases, where parasitaemia ranged from 10 to 125 000/mul of blood. The presence of high-titre antibody in the test preparations was found to reduce the sensitivity of parasite detection in infected RBC from in vitro cultures mixed with equal volumes of different antibody-containing sera. The sensitivity was restored in most cases by recovering the RBC by centrifugation before testing. In a preliminary experiment, there was no significant difference in antibody-binding inhibition using fresh infected RBC and RBC dried on filter-paper and recovered by elution, although there was greater variation in the latter samples.