Comments and Frequently Asked Questions About Immy Products
Immy's Latex-Crypto Antigen Test
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1. Why does IMMY require that serum MUST be DE
treated, but other companies do not require it?
Research,
both at IMMY and in the literature, has shown
that using DE (pronase) to treat serum is more
effective at releasing antigen from immune complexes
(e.g. increasing the titer).
2. What can cause FALSE positive reactions in the LATEX-Crypto Antigen Test?
We are currently aware of seven things that
can cause false positive reactions with specimens from patients not infected
with C. neoformans:
a. syneresis fluid (surface
condensate from agar culture medium)contamination of specimen, due to culturing the specimen before
latex testing;
b. contamination of specimen with talc,
from latex gloves;
c. patient infected with
Trichosporon beigelii;
d. use of siliconized tubes for serum,
or DE storage;
e. improperly cleaned ring
slide;
f. specimen containing
anticoagulant (e.g. EDTA);
g. rheumatoid factor in non-DE
treated specimen.
3. What can cause false negative reactions in the LA-Crypto Antigen Test?
We are currently aware of only two things
which can cause false negative reactions with specimens from culture-confirmed
cryptococcosis:
a. prozoning (we have only
received one report of prozoning and when the specimen was sent to IMMY, we
could not confirm the problem);
b. antigen bound in immune
complexes (e.g. antigen-antibody) which has not been released by digestion with
DE (pronase).
4. Why does IMMY require that DE (pronase) be aliquoted and frozen for storage, but other companies store the pronase in the refrigerator until use?
Research at IMMY has shown that IMMY's DE and another company's pronase decreased in activity by over 50% when stored at 2-8° C for 30 days. In experiments where the DE and pronase were frozen (-20° C or colder) for 30 days the enzyme activity decreased by less than 10%, compared to the activity of the original enzyme. The initial IMMY DE had almost four times greater enzyme activity than the other company's pronase, but both our DE and the competitor's pronase decreased under the same conditions at approximately the same rate.
5. Our laboratory is standardized on another company's test; does IMMY have a NCCLS format so that we would not have to retype our procedure?
YES! The procedure is available on the IMMY web site.
NOTE! You must have the Adobe Acrobat Reader, v.3 or higher which you can download free from
http://www.adobe.com
6. Why does IMMY use polyclonal antibody rather than monoclonal antibody on its latex?
IMMY has experimented with monoclonal antibodies several times and so far, has not found a monoclonal antibody that is sensitive to all four of the C. neoformans serotype antigens. IMMY routinely tests competitor's kits, which includes one company which uses a monoclonal antibody on its latex. Their product was not sensitive for purified cryptococcal polysaccharides; although the kit was positive with patient samples from cryptococcosis cases (the serotypes of the infecting organisms was not known).
In the US over 80% of the infections are caused by C. neoformans, var. neoformans, serotype A. The remainder are caused by other serotypes.
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Immuno Mycologics, Inc. 2003
Telephone:405-360-4669 Toll
Free: 800-654-3639 Fax:405-364-1058
2700 Technology Pl
Norman, OK 73071 U.S.A.
info@immy.com
Immy provides the most comprehensive line of diagnostic products available in the study of Mycology.
We offer a variety of fungal test products for the following organisms: Cryptococcus neoformans, Coccidiodes immitis, Histoplasma capsulatum, Candida albicans, Sporothrix schenckii,
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