Immunological crossreactivity of the antisera to purified hormones.

Antisera to ovine follicle stimulating hormone free of ovine lutinising hormone contamination has been obtained in monkeys. These antisera have been shown to be able to crossreact with ovine lutinising hormone. Quantitation of the binding data for ovine follicle stimulating hormone and ovine lutinising hormone show that 10–40% of the total antibody population to ovine follicle stimulating hormone can bind to ovine lutinising hormone and the affinity constant for ovine lutinising hormone is about 2–20 times lesser than for ovine follicle stimulating hormone. These binding data indicate that there are common epitopes exposed in ovine follicle stimulating hormone and ovine lutinising hormone through the α- subunit. Results are obtained which match with the above conclusions when ovine lutinising hormone antisera is analysed for ovine follicle stimulating hormone binding. These results show that the α-subunit when combined with different ß-subunits will have common epitopes exposed, but would be sterically disposed differently in the two hormones.