Oral scleral heterografts. A pilot study

Immunologic tolerance to collagen and glycosaminoglycan components of scleral allografts in humans. Evidence for T cell suppression

Unfractionated peripheral blood lymphocytes (PBL) and the T and B cell fractions of PBL from four patients who had received scleral allografts, and fractions from four control subjects were tested in vitro for proliferative responsiveness to collagen and glycosaminoglycan-enriched extracts of allogeneic sclera. None of the unfractionated lymphocyte cultures (patients and controls) were responsive to the scleral extracts. However, B-enriched lymphocyte cultures from one patient and two control subjects did respond to the scleral extracts, although there was considerable individual variation in the magnitudes of these responses (stimulation indices ranging from 1.5 to 11.5). In contrast, the DNA-synthesis response of T cells to scleral extracts was strongly suppressed. Furthermore, T cells pre-exposed for 24 hours to scleral collagen were capable of suppressing B-cell responsiveness to mitogens in autologous mixed lymphocyte cultures. Our findings confirm the lack of apparent adverse immunologic responsiveness to scleral allografts in humans as reported by others. It is possible that immunological tolerance to the scleral allografts is due to a suppressor T-cell mechanism which is triggered by scleral collagen.

Clinical and laboratory studies on human sclera allografts

In the first section of this two-part report human peripheral blood leukocytes were tested for reactivity to extracts of sclera. Absence of scleral antigenicity is suggested by the results which showed that the leukocytes reacted similarly in sclera stimulated cultures and in the controls. The second part of the report discusses the clinical aspects of sclera allografts and provides guidelines for their clinical use. A case is presented where a sclera graft was in position for approximately a year. The tooth was removed with the attached graft and a histologic study made.