A mouse monoclonal antibody reacting with swine leukocytes: a flow cytometrical and immunohistochemical study

A mouse monoclonal antibody (Mab) was prepared by immunization of Balb/c mice with porcine peripheral blood mononuclear cells. Its reactivity was studied by flow cytometry and immunohistochemistry. By flow cytometry 75-90% of blood lymphocytes and 93-97% of blood granulocytes showed positivity, while all monocytes were labelled. The specificity of the Mab was investigated further by immunohistochemical methods using different tissues of swine. Both cortical and medullary thymocytes strongly expressed the target antigen of Mab 335-2. Intensive staining of T cell dependent areas in the lymph nodes, spleen and tonsils was also observed. Many positive cells occurred in the red pulp of the spleen. In the non-lymphoid tissues no organ-specific staining was observed, except for the connective tissue which contained scattered positive cells. Kupffer's cells and some glial cells reacted with this Mab. These results suggest that this novel Mab recognizes a major antigen present on immature and mature T cells; however, subpopulations of myeloid cells (neutrophils, monocytes, and some types of macrophages) share this antigen.