Donald W. Mason

Monoclonal Antibodies That Define T-Lymphocyte Subsets in the Rat

All lymphocytes have the same morphological appearance, but they can be functionally split into two main categories. B lymphocytes differentiate in the bursa (avia) or bone marrow (mammalia) and give rise to antibody-secreting cells, while T lymphocytes differentiate in the thymus and are responsible for cell-mediated immunity (Moller, 1969). These differences in function and ontogeny correlate with the expression of different cell-surface molecules (antigens) on B and T lymphocytes and antibodies to these molecules have been important as markers for identifying and separating different cell types (Raff, 1971). The possibility that marker antigens have important functional roles is illustrated by the fact that cell-surface immunoglobulin (sIg) is a standard marker for B lymphocytes and is also the receptor for antigen on these cells.

The role of lymphocyte subpopulations in the transfer of rat EAE

The role of lymphocyte subsets in rat EAE was investigated using a passive transfer system in which spleen cells from sensitized donors were injected into naive recipients after incubation in culture for 72 h with myelin basic protein. The presence of anti-I-A antibody, but not anti-I-E antibody during incubation, prevented disease. In addition, removal of I-A+ cells by rosetting prior to injection eliminated the ability of the donor splenocytes from transferring disease while the simultaneous removal of both cytotoxic/suppressor and B cells had no effect on the disease outcome.

Evidence for an Immunosuppressive Autoantibody in Experimental Allergic Encephalomyelitis

Lewis rats immunized with myelin basic protein (MBP) in complete Freund’s adjuvant experience a single episode of paralysis and after recovery are refractory to further disease induction.’ The processes bringing about this refractory state, which may be similar to those involved in the remissions observed in multiple sclerosis, are still poorly understood. Here we examine in EAE the possible role of an immunoregulatory autoantibody found in convalescent animals. We consistently failed to adoptively transfer refractoriness to EAE with T lymphocytes, but serum from convalescent animals is a potent inhibitor of clinical signs (FIG. 1). This suppression is also seen when serum is transferred from animals immunized with whole brain homogenate in complete Freund’s adjuvant.’ Although

No observed role for CD8+ (suppressor/cytotoxic) T lymphocytes in the immunoregulation of EAE in the rat

Previous data from our laboratory show that microglia cultured from normal mice, as well as mice infected with scrapie agent, stain with nucleoside diphosphatase, a marker of CNS mesodermal cells, and are negative for gli81 fibrillary acidic protein (Merz, et.al. Acta Neuropathol. 72:240-247, 1987). Microglia and macrophages share a number of characteristics. Our current data demonstrate the production of interleukin-I from microglia derived from both normal and scrapie infected mice. In addition to Mac-I surface marker, microglia from scrapie infected mice are positive for F4/80 antigen, a surface marker for mature macrophages.