New Zealand White rabbits were injected intravitreally with approximately 2,500 viable or heat-killed meningococci. The rabbits were killed at intervals from 30 min to 14 days after injection. None of the rabbits produced detectable antibodies. Local antibody production by uveal tract, spleen, or preauricular lymph node cells was not demonstrated. Viable organisms were recovered from the vitreous at periods from 30 min to 48 hr after injection. Failure to recover viable organisms could be correlated with the appearance of large numbers of polymorphonuclear neutrophiles (PMN) throughout the vitreous. Animals injected with viable meningococci demonstrated a progressive inflammatory reaction characterized by an early accumulation of PMN in the vitreous, limbus, and conjunctiva. The cellular infiltrate gradually became mononuclear. By the 14th day postinjection only a few residual inflammatory cells remained at the limbus. This extensive cellular response was lacking in recipients of heat-killed organisms. The defense of the rabbit against intraocular introduction of meningococci therefore seems to be predominantly a cellular mechanism.

The experiments described were undertaken to determine which cells of guinea pigs immunized by different ocular routes produce the IgG1 and IgG2 antibodies detected in the serum. Guinea pigs were immunized intravitreally, topically, or by intravitreal immunization followed by topical conjunctival challenge. An indirect plaque assay was used to detect antibody producing cells in the cervical lymph nodes and ocular tissues. Passive hemagglutination, passive cutaneous anaphylaxis and ELISA assays were used to detect serum antibody. Both the topical and intravitreal methods initiated a primary antibody response. The guinea pigs developed IgG1 and IgG2 serum antibodies, but IgE and IgA antibodies were not detected. IgG1 and IgG2 plaque forming cells (PFC) were found in the lymph node and uveal tissues of the intravitreally immunized guinea pigs, and in the lymph node and conjunctival tissues of the topically immunized animals. IgA plaque forming cells were not detected in topically immunized animals. No antibody producing cells were found in intravitreally immunized guinea pigs sacrificed after the first conjunctival challenge (two months after sensitization). The highest numbers of lymph node and conjunctival PFC were found in the animals sacrificed three days after the second or third topical challenge. The numbers of IgG1 antibody producing cells in this group of guinea pigs were usually higher than the numbers of IgG2 PFC. Serum antibody levels, undetectable before challenge, increased after the second challenge. We conclude that both lymph node and ocular cells produce antibody in guinea pigs immunized by ocular routes.

NOTICE: Mhen goverment or other dravings, specifications or other data are used for any purpose other than in connection with a definitely related goverment procurement operation, the U. S. Government thereby incurs no responsibility, nor any obligat~ion vhatsoever; and the fact that the Government may have formilated, furnished, or in any vay supplied the said dravings, specifications, or other data is not to be regarded by iMplication or otherwise as in any manner licensing the holder or any other perhon or corporation, or conveying any rights or permission to manufacture, use or sell any patented invention that my in any vay be related thereto. us=nDm629 •~1 Mur cz-h 1963, CONSTRCTION O A MK 7IFED BERSON APPARATUS N by SJ.

No abstract