THE FINE-STRUCTURE OF NORMAL LYMPHOCYTE SUB-POPULATIONS - A STUDY WITH MONOCLONAL-ANTIBODIES AND THE IMMUNOGOLD TECHNIQUE

Abstract

Ultrastructural characteristics of normal [human] lymphocyte subpopulations, identified by monoclonal antibodies and visualized by a colloidal gold labeled anti-mouse IgG were analyzed. The major T lymphocyte subsets (OKT4+ and OKT8+) have distinct ultrastructural morphology. The majority of OKT4+ cells have a high nuclear/cytoplasmic ratio (N/C) and few cytoplasmic organelles while most OKT8+ cells have a low N/C ratio and numerous organeles, namely a well developed Golgi apparatus, lysosomal granules and parallel tubular arrays (PTA). A unique subtype with irregular nuclear outline that resembles Sezary cells was seen in 5-10% of OKT4+ lymphocytes. OKM1, a reagent that reacts with monocytes and granulocytes, is positive in a small lymphocyte subset which appears to be negative with the OKT reagents and is morphologically identical to OKT8+ cells. Hand-mirror cells were only seen labeled with OKT8 and OKM1. B lymphocytes labeled with FMC4 (anti-IA) were distinguished from OKT3+ lymphocytes by having numerous profiles of endoplasmic reticulum (ER) and ribosomes; these were particularly prominent in lymphoplasmacytoid cells. Morphological similarities between normal T lymphocyte subsets and T neoplasias of the same membrane phenotype suggest that these disorders arise from specific T cell types present in normal peripheral blood or from common precursors.