DEMONSTRATION OF CYTOPLASMIC CD32 (FC-GAMMA-RII) WITHIN HUMAN-LYMPHOCYTES FOLLOWING MICROWAVE TREATMENT

We have recently described a cytoplasmic form of CD32 (Fc gamma RII) w ithin the vast majority of normal human peripheral blood lymphocytes ( PBL) including T cells. The function of cytoplasmic CD32 is not known. These flow cytometric studies were conducted using single cell suspen sions of PBL that had been pre-fixed and permeabilized using methanol/ triton-X-100. In this study we have attempted to visualize cytoplasmic CD32 by immunocytochemistry using normal PBL processed in various way s and have also looked for CD32 within tissue lymphocytes. Weak cytopl asmic CD32 staining was observed in paraffin sections of normal lympho cytes but only when sections were microwave treated. The intensity of staining for CD32 did however, appear to be much stronger within infil trating lymphocytes found in autoimmune diseases or in rejecting allog rafts: an observation that suggests that up-regulation of cytoplasmic CD32 may occur when T cells become activated in vivo. Microwave treatm ent of PBL suspensions was shown to disrupt the outer cell membrane, t hus effectively permeabilizing the cell, and allowing for the detectio n of cytoplasmic components, like CD32, by flow cytometry. Microwave t reatment may, therefore, afford an alternative method for cell permeab ilization and may prove to be a useful method for the study of cytopla smic molecules in cell suspensions and in paraffin-embedded tissues.