Nonbursal origin of humoral immunity: immune capacity and cytomorphological changes in chickens bursectomized as 52- to 64-hours-old embryos.

Chickens sham-bursectomized as 52- to 64-hours-old embryos (SBx), chickens bursectomized at hatching (NeoBx) and chickens from which the bursal primordium was removed at 52-64 h of embryonation (EBx) were immunized with guinea pig red blood cells when 21 days old. Following the second injection of antigen, EBx chickens were found to elaborate ME-sensitive and ME-resistant hemagglutinins, to produce direct and indirect plaque-forming cells, and to contain lymphocytes bearing a specific bursa (Bu) antigen. These immune properties were more often expressed in sham-bursectomized and neonatally bursectomized chickens. Cytomorphological changes in the spleen, bone marrow and cecal tonsil of EBx chickens were typical for birds lacking the bursa. The number of lymphocytes and plasma cells in the bone marrow and liver of SBx, NeoBx and EBx chickens was very low. These results suggest that a very early embryonic bursectomy of chickens does not abolish humoral immunity completely and does not prevent the differentiation of Bu antigen-bearing lymphocytes.

Preparation of specific anti-thymocyte and anti-bursacyte sera in rabbits.

A method of producing anti-thymocyte and anti-bursacyte sera in rabbits is described. Chickens which served as donors of cells were thoroughly perfused with saline to remove plasma proteins and circulating blood elements. For immunization, thymocytes were obtained from neonatally bursectomized birds, and bursacytes from chickens thymectomized at hatching. The purification of rabbit anti-lymphocyte sera included absorptions with leucocyte-free suspension of chicken erythrocytes, chicken liver cell membranes, thymocytes from bursectomized-irradiated and bursacytes from thymectomized-irradiated chickens, and chicken IgM and IgG immunoadsorbents. Cytotoxicity and fluorescent-antibody assays revealed that anti-thymocyte and anti-bursacyte sera thus produced clearly distinguished the surface antigenic determinants of thymocytes from those of bursacytes.

Thymic microenvironment in myasthenia gravis.

This study was undertaken to investigate the role of thymic epithelial (TE) cells in the immunopathology of myasthenia gravis (MG). Seventeen thymuses from patients with MG and six normal thymuses were investigated by light and electron microscopy, using a stereologic method. In the myasthenic thymuses the cortex was markedly reduced, while the medulla was hypertrophied and had numerous germinal centers. A subpopulation of cortical TE cells showed a large fibrillar nucleolus and a decreased number of cytoplasmic dense bodies and cysts, indicating decreased function. Medullary TE cells, on the other hand, showed evidence of increased activity with an enlarged euchromatic nucleus and an increased number of cytoplasmic dense bodies. There was a statistically significant negative correlation between the decrease in size of the thymic cortex and the appearance of medullary germinal centers. A significant correlation was also demonstrated between atrophy of cortical TE cells and depletion of cortical thymocytes. Our study shows that both cortical and medullary TE cells are involved in the pathogenesis of MG but have different roles.

Ontogeny of this immuno-neuro-endocrine relationship. Changes in lymphoid tissue of chick embryos surgically decapitated at 33-38 hours of incubation.

The prosencephalon, and primordium of the hypophysis were surgically removed from chick embryos at 33-38 hours of incubation. The thymus, bursa of Fabricius, spleen, bone marrown and liver were examined cytomorphologically on day 15, 17 and 19. T marker-bearing and Bu marker-bearing lymphocytes were identified by immunofluorescence. Decapitated embryos tended to be smaller than sham-decapitated controls of the same age, and exhibited retarded development of the thymus, bursa, spleen and liver. Decapitation particularly affected the cellular composition of the bursa and spleen, induced a decrease in the number of lymphocytes, and caused a striking depletion of lymphocytes bearing Bu antigen. This experiment showed an interdependence between lymphoid (immune), nervous and endocrine centers in the chick embryo.

Thymus changes in experimentally induced myasthenia gravis.

Experimental myasthenia gravis (EMG) was elicited in female AO rats, 8-12 weeks of age, by injection of 100 micrograms/rat Torpedo marmorata acetylcholine receptor (AChR)-protein incorporated in CFA. Bordetella pertussis, 24 x 10(9) microorganisms, rat, was injected simultaneously as additional adjuvant. Rats were sacrificed on the day of appearance of the clinical signs of EMG, and thymuses were used for histological analysis using stereologic method, and thymocyte subsets were estimated by flow cytometry. Two and three colour fluorescence was applied to determine DN (CD4-CD8-), DP (CD4+CD8+), SP-CD4+ (CD4+CD8-) and SP-CD8+ (CD4-CD8+) subsets, as well as thymocytes expressing TCR alpha/beta. Rats immunized with BSA and rats injected with saline were used as controls. From 56 rats immunized with AChR-protein, 44 rats developed the disease, between day 7 and 11 after immunization. Severity of disease varied from + to + + +. Stereologic analysis of tissue sections revealed a highly significant reduction of thymic cortex and hypertrophy of medulla in EMG thymuses. Similar, but very slight changes were observed in thymuses of rats immunized with BSA. Percentages of DN, SP-CD4+, and SP-CD8+ subpopulations were significantly increased, while the percentage of DP population showed a marked decrease. These preliminary data suggest an alteration of thymocyte maturational events. Whether these changes could be responsible for the initiation of autoimmunity, or are occurring as a secondary phenomenon, after EMG was already established following the injection of cross reactive antigen, is a matter for discussion.

Cation-induced immunosuppression: the effect of lithium or Arthus reactivity, delayed hypersensitivity and antibody production in the rat.

Arthus reactivity and delayed skin sensitivity to bovine serum albumin (BSA), and anti-BSA antibody production were markedly impaired in female Wistar rats repeatedly injected with lithium chloride.

Ia+T10+ blast cells in acute lymphoblastic leukaemia are precursors of T+ and B+ cells.

Leukaemic blasts isolated from peripheral blood of two patients with non-T, non-B ALL were cultivated for 10-13 days and cell markers were assayed on day 0 and during culture period. Using a panel of cell markers it was demonstrated that the populations of ALL blasts of both patients were composed of T10+Ia+ and "null" blasts. These blasts in the culture differentiated into three cell lines: T and B lymphocytes and myelomonocytic cells. The results thus obtained suggested that within the population of ALL blasts of these two patients there are progenitors of lymphoid and myelomonocytic cells ("null" blasts) and common precursors of T and B lymphocytes (T10+Ia+ blasts). In vitro differentiation of ALL blasts was not affected by LPS and CTPE.

Involution of bursa of fabricius in male and female chickens: a light microscopic histoquantitative study.

A histoquantitative study of the bursa of Fabricius in 3- and 6-month-old male Prelux Bro chickens (domestic selection) was made. All compartments of normal bursal tissue were examined. At 3 months of age, there were no significant differences in bursal weight and structure between males and females. The only difference observed was the higher volume density of follicular cortex and the lower proportion of follicular medulla in males compared to females. In 6-month-old male and female chickens, a different degree of bursal involution was observed. In the bursa of males, an advanced stage of involution was observed, whereas only the initial signs of bursal involution were found in females.

Effects of neonatal gonadectomy on the differentiation of prolactin and growth hormone cells in the chicken adenohypophysis: a quantitative electron microscopic study.

The ultrastructural stereological analysis of prolactin, growth hormone, and gonadotroph cells in the hypophysis of neonatally gonadectomized, 3-month-old male and female chickens was performed. The observed ultrastructural changes (especially of granular endoplasmic reticulum and content of secretory granules) demonstrated reduced biosynthetic activity of prolactin cells in neonatally ovariectomized females and increased activity of prolactin cells in neonatally orchidectomized male chickens.