Immunoelectron microscopic application of monoclonal antibodies for identification of lymphocyte subsets bearing tubuloreticular inclusions or parallel tubular arrays.

Reactions of mouse monoclonal antibodies with T-cell, B-cell, or NK cell antigens were localized for electron microscopy by the formation of avidin-biotin-peroxidase complexes using direct or indirect labeling techniques. The techniques proved advantageous for identification of lymphocyte subsets bearing two different types of cytoplasmic structures: tubuloreticular inclusions (TRI) which have been related to interferon treatment or to diseases involving systemic immune dysfunctions, and parallel tubular arrays (PTA) which may be normal structures. Mononuclear cell samples were isolated from the peripheral blood of patients with systematic lupus erythematosus (SLE), acquired immunodeficiency syndrome (AIDS), or chronic hepatitis B (CHB). Results depended upon the fixation, the type of specific antibody, and the concentrations employed. Brief fixation in 1% glutaraldehyde/1% paraformaldehyde proved useful for stable preservation of both the inclusion fine structure and surface antigen activity, even after prolonged storage in buffer. The T-cell subset antigens (Leu-2a and Leu-3a) were more labile than the pan-T-cell antigen (Leu-1), the B-cell surface antigen (Leu-10), or the NK cell antigen (Leu-7). Localization of the former was improved by a two-step labeling procedure with primary and secondary antibodies. Both TRI and PTA were identified in T cells. Either type of inclusion could be found in the suppressor/cytotoxic or helper/inducer T-cell subsets. TRI also were found in a few anti-Leu-10 reactive cells. A crystalline form of PTA was identified in anti-Leu-1 and anti-Leu-7 reactive cells.