The immunopathology of trachoma: Some facts and fancies

Conclusions

In writing this paper I have made an attempt, inadequate though it is, to seek explanations for some of the more puzzling manifestations of ophthalmic infections caused by TRIC agents. We have in the past possibly taken too naive a view of these syndromes, regarding features such as follicles and pannus purely from the viewpoint of a simple inflammatory process, and without giving enough consideration to the immunological mechanisms that may contribute to their causation. A quotation fromWilson andMiles' textbook (37) is apposite: “It is probable, indeed, that an increased sensitivity, associated with an increased vigour of response, is of frequent, perhaps almost of constant, occurrence at one stage or another of every infective disease, and that this sensitization plays a part in pathogenesis, particularly in subacute or chronic infections.”

The relative importance of humoral and of cellular factors in determining immunity to trachoma and the onset of healing is still not clear. Perhaps our thoughts on the immunopathology of PLT infections are still conditioned, even if subconsciously, by the erstwhile concept of the viral nature of these micro-organisms; and too much attention has been paid to the role of circulating antibody and not enough to that of cellular immunity. Nevertheless, the bacterial affinities of these agents, first pointed out byBedson andBland (1) and so admirably summarized byMoulder (23), lend plausibility to the idea that allergic reactions similar to those induced by bacteria may play an important role in pathogenesis.

In conclusion, it is apparent that my initial warning that I intended to provide more questions than answers has been amply fulfilled. My only justification is that some at least are open to experimental investigation; and although my colleagues and I cannot possibly tackle them all, we are now, we hope, working toward some of the solutions.