RESUMEN
Griffonia simplicifolia agglutinin I-B4 (GSAI-B4) has broader specificity for B antigen variants and can recognize the antigens in a wide variety of human tissues. Thus, the concentration range of GSAI-B4 required for staining and the susceptibility of staining to alpha-galactosidase digestion is presumed to correlate well with the density of B antigens in tissue sections. By microphotometric quantification of staining intensity at different concentrations of GSAI-B4 with or without alpha-galactosidase digestion, concentration of B antigens in selected tissues was evaluated and compared. Based on the present results and the previous ones of direct measurement of galactose of B antigens in sublingual glands and red blood cells (Ito et al., 1993), the order of concentration of B antigens in tissues examined was estimated as follows; mucous cells of sublingual glands from German nonsecretors < red blood cells and vascular endothelial cells (= 2.7 x 10(-3) nmole/cm2), thyroid papillary carcinomas and Hassall's corpuscles from nonsecretors < mucous cells of sublingual gland from Japanese nonsecretors < pancreatic acinar cells from both secretor and nonsecretors, Hassall's corpuscles and kidney collecting tubules form secretors < mucous cells of sublingual gland from secretors (> 8.5-11.7 nmole/cm2) and mucous cells of Brunner's gland from nonsecretors < mucous cells of Brunner's gland from secretors. From the above estimation, it is apparent that the expression of B antigen in Brunner's gland is partly dependent on the secretor status of individuals and that Japanese nonsecretors secrete substantial amounts of B antigens from sublingual gland while German nonsecretors do not. The present results also revealed an unexpected staining behavior of GSAI-B4 in some tissues, i.e. in mucous cells of sublingual glands and collecting tubules of kidney from secretors, staining intensity was markedly depressed at higher concentration of the lectin and this depression was recovered by prior alpha-galactosidase digestion. In addition, the present method was successfully applied for the estimation of the content of B antigens neo-expressed in thyroid papillary carcinomas, showing that the content of B antigen had a similar level to that of red blood cells and vascular endothelial cells.