Lymphocytes. 2. Differentiation. Differentiation of lymphoid precursor cells

The effect of steroids on the circulating lymphocyte population--VI. Studies of the thoracic duct T- and B-lymphocyte populations after neonatal thymectomy and prednisolone treatment. An immunofluorescence study in the rat

The corticosteroid effect on circulating lymphocytes in a steroid-sensitive species (rat) was studied by immunofluorescence. Both normal and neonatally thymectomized animals were injected with a high dose of prednisolone. T- and B-lymphocytes as well as T-lymphocyte subsets were analyzed in thoracic duct lymph during the involution phase (3 h after injection) and the restitution phase (17 h after injection) using conventional and monoclonal antisera. Neonatal thymectomy significantly reduced the number of circulating T-helper and T-non helper cells. In the involution phase, after a corticosteroid injection, there was a 64% reduction of lymph cell content in normal rats, affecting both T- and B-lymphocytes. Thymectomized animals showed an even more pronounced disappearance of cells. Counted in percentage, more B- than T-lymphocytes disappeared from the circulation. The T-non helper cells disappeared to a greater extent than the T-helper cells did. Cells with Ia-antigen showed about the same values as the B-lymphocytes. During the restitution phase all cells types were restored to normal levels. It seems that a high prednisolone dose has a more pronounced effect on the circulation of B- than of T-lymphocytes, and the T-non helper cells are probably more sensitive than the T-helper subpopulation. These data support the hypothesis that a major corticosteroid effect is a trapping and redistribution of circulating lymphocytes, more pronounced for certain cell types.

Nuclear morphology and morphometry of B-lymphocyte transformation. Implications for follicular center cell lymphomas

One of the major tenets of current non-Hodgkin's lymphoma classifications is the relationship of morphologic subtypes to stages in the sequence of normal B-lymphocyte transformation occurring in the germinal follicle. To test this hypothesis, quantitative morphometric image analysis was carried out on in vivo and in vitro samples of mouse splenic lymphocytes in which transformation was induced by bacterial lipopolysaccharide (LPS), a specific B-cell mitogen. The results were compared with a similar analysis of germinal center lymphocyte populations of normal human spleen. In the in vivo mouse model, initial stages of B-cell transformation were detectable as early as 4 hours after LPS injection, and the process was essentially fully developed by 48-72 hours. Quantitative evaluation revealed that the majority of nuclear profiles were nearly spherical or only slightly eccentric and that no major alteration in nuclear contour occurred during any phase of the progressive increase in nuclear size following mitogen-induced lymphocyte transformation. In fact, in this system, B lymphocytes with a nuclear profile cleft of greater than or equal to 0.4 mu accounted for only 3% of the combined unstimulated and LPS-activated population assessed (N = 9936). This compared with normal human spleen, in which 16% of germinal center lymphocyte populations had similarly cleft nuclear profiles. Sequential alterations in the organization of condensed chromatin occurred concomitant with gradual nuclear enlargement during mitogen-induced mouse spleen lymphocyte transformation. A comparative morphologic and morphometric assessment of nuclear profiles of lymphocyte populations in germinal centers of normal human spleen provides indirect evidence for a similar pattern of nuclear alterations in human B lymphocytes. Autoradiographic data obtained from LPS-activated mouse splenic lymphocytes indicate that nuclear morphologic aspects of the transformation process can occur entirely within the G1 phase of the cell cycle. The results of this study suggest that subtypes of non-Hodgkin's lymphoma largely composed of neoplastic lymphocytes with extensively convoluted or cleft nuclei do not reflect a morphologic stage in the transformation of normal lymphocytes. In addition, the heterogeneous nuclear forms of follicular center cell lymphocytes would appear to result from parallel transformation processes involving cleaved and noncleaved nucleated lymphocytes and not the sequential pathway proposed by Lukes and Collins.

Differential diagnosis of malignant lymphoma and nonlymphoid tumors using monoclonal anti-leucocyte antibody

Pathologic samples from 34 cases of human solid malignancies were tested for reactivity with monoclonal anti-human leucocyte antibody, designated 2D1. This antibody detects a human leucocyte antigen (HLe-I) that is expressed strongly on B and T lymphoid cells and weakly on early hemopoietic cells, but is not found on normal mesenchymal and epithelial tissues. This study demonstrates the use of this reagent in cryostat sections of tumor samples using indirect immunofluorescence in combination with other lymphoid markers such as anti-T cell serum, anti-Ia-like serum (detecting p28, 33 "B cell associated" membrane antigen) and antisera to different immunoglobulin isotypes. Tumor cells from all 12 cases of epithelial malignancies and sarcomas were HLe-I- although adjacent (normal) lymphoid cells showed strong positive staining. In contrast, 20 cases of lymphoma (B- as well as T-cell types) were HLe-I+. Two other malignancies involving the lymphoid system were HLe-I- and failed to express any of the other lymphoid markers tested.

The presence of HLA-DR antigens on lactating human breast epithelium and milk fat globule membranes

HLA-DR antigens have been demonstrated on the secretory epithelia of lactating breast using rabbit anti-p28,33 ('Ia-like') and mouse monoclonal anti-HLA-DR 'framework'. Normal non-lactating breast, benign or malignant tumours, epithelial cells from normal breast or isolated from milk and a presumptive breast carcinoma cell line (MCF-7) were all HLA-DR-negative. HLA-DR, HLA (ABC 'framework') and beta 2-microglobulin determinants were also demonstrated on the surface of milk fat globules (MFG) which were unreactive with monoclonal antibodies to thymus cells or leucocytes. A monoclonal antibody detecting allelic HLA-DR determinants (HLA-DRw 1,2,6) was positive on 40% of MFG samples tested, positive reactions being concordant, when tested, with blood B lymphocytes. Antisera raised against MFG membranes also contain anti-HLA-DR activity. Whether the breast epithelial cells synthesize HLA-DR molecules or acquire these passively from mononuclear cells which infiltrate during lactation is not yet resolved.