Decreased fertility in female mice immunized with a carrier followed by small numbers of spermatozoa.

It has been conclusively shown that immunization of female mice with spermatozoa can significantly decrease their fertility (McLaren, 1964, 1966; Edwards, 1964; Bell, 1969; Bell & McLaren, 1970). All of the work by McLaren and Bell (McLaren, 1964, 1966; Bell, 1969; Bell & McLaren, 1970) has involved very extensive courses of immunization: from twenty-one to twenty-four injections of 6 to 15 \m=x\106 spermatozoa or fractions thereof. Edwards (1964) used shorter and more varied immunization schedules, with three to eleven booster injections in different individuals of one experimental group, and found a smaller effect on the number of eggs fertilized than McLaren and Bell found on the number of liveborn offspring (McLaren, 1964, 1966; Bell, 1969; Bell & McLaren, 1970). However, none of the female mice in Edwards experiments received fewer than 30 \m=x\106 spermatozoa. This paper reports significant decreases in the fertility of female mice immunized with 15 IO6 spermatozoa by utilization of the carrier effect ('cooperativity'). Random-bred Swiss Webster mice were mated before sensitization and only fertile pairs were used in the experiment. A patch, 5 to 6 cm2, was shaved on the belly of the females and 0-05 ml of 0-5% l-fluoro-2-4-dinitrobenzene (FDNB) in a mixture of acetone and olive oil was applied three times at 10-day intervals by painting on the skin. This quantity and dosage schedule had been found to give maximal delayed hypersensitivity to dinitrophenol (DNP) in the CBA strain of mice (Taylor & Iverson, 1971). Ten days after the last skin-painting, cultured human lymphocytes or spermatozoa from the epididymides and vasa deferentia of Swiss mice (prepared as in Erickson, 1972a) were treated with DNP by a modification of a published method (Bauminger & Yachnin, 1972) : 50 IO6 cells were suspended in 5 ml phosphate-buffered sahne and 2 vols of 0-05 M-EDTA, pH 8-4 and 25 μ 0-1 m-FDNB in acetone were added ; the mixture was incubated for 15 min at 37° C, and the cells were washed twice in 0-025 M-EDTA, pH 7-4, 0-075 M-NaCl, and 0-05 M-glucose. Cells (5 IO6) per animal