Why is the infectious stage of syphilis prolonged?

Cell-mediated immunity during syphilis. A review

“…Other experiments performed by Laird and Thorburn (1966) showed that 67% of their patients with tertiary syphilis gave delayedtype hypersensitivity reaction to an extract of T. pallidum, the luotest, which occurred after repeated challenge. The unresponsiveness in early syphilis seems to be specific to T. pallidum antigens since skin reactions to several non-treponemal antigenssuch as, mumps, old tuberculin, and varidasewere reported in patients at various stages of syphilis (Wright and Grimble, 1974). Some investigations have been performed relating the histological appearance of lymphoid tissues with the presence of T. pallidum infection.…”

“…In addition it is becoming apparent that the cellular limb of the immune response is defective in the highly infectious early stages of syphilis and is mobilised at other stages. Antigenic competition has been considered a possible candidate underlying the hyporeactive state in early disease (Wright and Grimble, 1974). If T. palliduni possesses multiple antigenic determinants (and this seems likely) one antigen could selectively compete and interfere with the response to other antigens, thereby creating a condition of partial or split tolerance.…”

Alterations in T lymphocytes and T-lymphocyte subpopulations in patients with syphilis.

“…The importance of cell-mediated immunity (CMI) in syphilis is suggested by T-lymphocyte depletion in the paracortical areas of lymph nodes and the periarteriolar area of the spleen in children with fatal congenital syphilis.9 10 In rabbits, the infection takes a severe course if T lymphocytes are destroyed by cyclophosphamide treatment." In patients with syphilis evidence has been found for a depression in CMI, which involves cutaneous reactivity, ' low T-cell numbers,6 low in-vitro reactivity to Treponema pallidum, 1 3-5 and immunosuppressive factors in serum.…”

Ultrastructural study of satellite lymph nodes in syphilitic rabbits.

“…Unusual findings have included histiocytic infiltration of the paracortex and the presence of what appear to be plasma cells in germinal centres; in normal lymph nodes or in other infections these cells are usually confined to medullary areas (Turner and Wright, 1972). Infection with Treponema pallidum is accompanied by alterations of immune regulation affecting antibody production and cell-mediated immunity (Wright and Grimble, 1974;Musher et al, 1977); these include production of non-treponemal antibody (Turner and Hollander, 1957;Turner, 1970), suppression of the IgG response to a thymusdependent antigen such as sheep red blood cells (Baughn and Musher, 1978), delayed production of lymphokines (Wicher and Wicher, 1977), and suppressed lymphocyte transformation to a variety of antigens and mitogens (Levene et al, 1969;Musher et al, 1974;Friedman and Turk, 1975;Musher et al, 1975Musher et al, , 1977Pavia et al, 1977). In the light of these abnormal immune responses we have undertaken an electron microscopy examination of lymph nodes from syphilitic rabbits.…”