Laboratory on Cellular Neuropharmacology, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 20632, Caracas 1020A, Venezuela. Electronic address: firstname.lastname@example.org.
We used high sensitivity and resolution fluorescence microscopy to study the interaction of ostrich IgY, horse F(ab')(2) and horse IgG with mice lymphocyte and erythrocyte plasma membrane. The immunoglobulins were labeled with fluorescein isotiocyanate (FITC). Our results show an interaction of IgY with lymphocyte plasma membrane which does not result in endocytosis of the labeled protein. Less IgG and its F(ab')(2) fraction bind to lymphocytes, and this binding seems to be followed by endocytosis producing a diffuse cytoplasmic fluorescence in most lymphocytes exposed to FITC-IgG or FITC-F(ab')(2). Cytoplasmic fluorescence resembling FITC was not observed in lymphocytes exposed to FITC-IgY. Receptors in the erythrocyte membrane also differentiate between avian and horse Ig; while erythrocytes exposed to horse Igs became intensely fluorescent for at least 5 h, no erythrocyte labeling occurred when FITC-IgY was used. Our results suggest that IgY may be a stronger activator of adaptive immunity than horse IgG in mammals. Adaptive immunity against IgY is detrimental to its IV therapeutic use in humans and other mammals.
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