Gm. Centola et al., COMPARISON OF THE IMMUNOBEAD BINDING TEST (IBT) AND IMMUNOSPHERES (IS) ASSAY FOR DETECTING SERUM ANTISPERM ANTIBODIES, American journal of reproductive immunology [1989], 37(4), 1997, pp. 300-303
PROBLEM: The IBT is considered the gold standard of sperm antibody ass
ays. This test uses polyacrylamide beads labeled with antiglobulins (a
nti-IgG, anti-IgA, and anti-IgM), which bind to the corresponding anti
body on the sperm surface. The IS uses color-coded latex beads of unif
orm 3.0 mu m size coated with the antiglobulins which can be viewed wi
th brightfield light microscopy. The purpose of the present study was
to compare the IBT and IS in an indirect test using human serum. METHO
D: Serum specimens (n=42) were tested for the presence of antibody iso
types IgG, IgA, and IgM to sperm using the standard protocol for IBT a
nd IS. Donor sperm was washed in BWW with 5% BSA and diluted to a fina
l concentration of 50 x 10(6) motile sperm/ml. The sperm were incubate
d with a 1:10 dilution of test serum for 30 min to 1 h at 37 degrees C
and then washed by three cycles of centrifugation. The sperm and bead
s (IBT, IS) were mixed on a glass slide, covered with a coverslip, and
observed within 5 min. At least 100 motile sperm were counted and sco
red for bead binding. A specimen was considered positive if 20% or mor
e of the sperm were coated with one or more beads. The data were analy
zed using calculation of the non-parametric kappa statistic with corre
ction for chance expected agreement, and by calculating the proportion
of specific agreement between the two methods. RESULTS: The results a
re summarized in the following table: [GRAPHICS] The IS was able to de
tect 94% of IgG antibodies, 91% of IgA antibodies, and 100% of Ig M an
tibodies. One serum specimen was IgG negative by IS (14% binding), but
positive by IBT (20%). A second serum specimen was IgA negative by IS
(16%) yet positive by IBT (29%). There were no false positives with t
he IS assay. Of the IgM positives (five of six) occurred alone and not
with IgG or IgA, suggesting the necessity for testing all specimens a
lso for IgM. CONCLUSION: Antisperm antibody test results obtained by t
he IS assay are in agreement with the results obtained with the IBT te
st. The Immunospheres are monodispersed, color coded, and can be visua
lized with brightfield microscopy.