INVITRO STUDY OF THE BINDING OF ANTI-RIBONUCLEOPROTEIN ANTIBODIES TO THE NUCLEUS OF ISOLATED LIVING KERATINOCYTES

[摘要] The general accepted dogma is that antibodies do not penetrate living cells. This was recently challenged for anti-ribonucleoprotein antibodies (anti-RNPab). The penetration of trypsin isolated [guinea pig] keratinocytes in vitro was studied using indirect immuno-fluorescence and immuno-peroxidase techniques. Some 70% (.+-. 22) of a living keratinocyte cell suspension showed nuclear speckled staining when incubated with anti-RNP sera but only 9.5% (.+-. 4) were stained with an anti-DNA antiserum (homogeneous pattern). A suspension of dead keratinocytes gave similar percentages with both anti-sera (89.5 [.+-. 8] and 76.6 [.+-. 18], respectively). Anti-RNPab penetration into the nuclei of living epidermal cells increased gradually during the 1st h of incubation without a parallel increase in the death rate measured by trypan blue dye exclusion. There was still a high percentage of stained cells even after high dilution (1/1000) of anti-RNP sera. The percentage markedly decreased after previous incubation of the cells with increasing concentrations of concanavalin A. No decrease was obtained with dead keratinocytes in the same conditions. After they were incubated with anti-RNPab, the epidermal cells were still capable of adhering to culture flasks and of incorporating labeled precursors. Only 4% of the epidermal cells in suspension were able to form rosettes with antibody coated erythrocytes, and were thus bearing receptors for the IgG Fc fragment. Apparently anti-RNPab penetrated living epidermal cells, but not through Fc receptors as reported for mononuclear blood cells.