Effects of X‐irradiation on Antigen Localization in Lymphoid Follicles

Abstract

Summary. Tlic effects of whole hotly X-iiradiation hcltirc or alter tlic iiijcclinn ol '-"•l-fal>('llc<f SatiiKinctta flajifllar aiitijiciis on (ii) anlilindy prnduftiiin ant! (h) iintiyfii tlistrihiitioii lliroiiyli tlu' lyiiiplioid sysEi'iii were iii\i'stijiattMi.\\ hole hotly X-jrratliatioii (4.50 H) catLsed marked tiepre.ssion tif lioth y\l and yi'. responses if givt'ii one t!ay before antigen. With a liiuli dose oi the stronj^est antiyen. hut not with a low tlose or with the weaker antijjen. two fnrtlit'i" iibservalioiis were made: (a) colchicine could restore anlihotly-formin)ĉ apacity, anti (h ) X-ray ni\'en after antigen actually causet! an enhanced innnune response.\-irratliatit)u causctl subtle l)ut inipt)rtant chanjfcs in antigen fiicalization. Tlie anattimiciil structure, presumably cytoplasniic fibrils, in tlie iymphiiiti lollifles responsihle for antifjen Irapping was rt'iiuirlcably rath'< ires i.s tan t. Little damage coultl he nbser\ecl with iloses less than 12.50 K. and it took 8000 li lo deslniy the structure completely. IIowe\fr. the lollicular mechanism was not lunctidTially intact. Spleen antoradioyriiphs and whole orjian counts showed a lowered capacity t»f the web U> retain aiitiyen. Lymph n<ide autoradionraphs showet! abnormal persi.stence (if lahellin^ in a snbsinus rim of cortical pliant>-cyles. Thi.s was interpreted to intlicate an X-ra>' intlnceil interference with antigen niijjratiiin, X-irratliation had im oliM-rwiblc ellect on the sinus macrophages of the hinpli node metliilla. This once again snggests that their function is less spcciali/ed thau that of the follic'nlar antigen-retaining cells.INTRODUCTION.

The origin of follicular dendritic cells in the mouse and the mechanism of trapping of immune complexes on them

“…Nevertheless they confirm the early observations of Jaroslow and Nossal [17] and of Nettesheim and Hanna [18] that rat or mouse FDC with trapped radiolabeled antigens are not destroyed by irradiation up to 18.5 Gy, although even after 4.5 Gy their capacity to hold antigens is gradually impaired. Ingenious experiments by Brown et al [3] indicated that a radiosensitive population of presumptive B lymphocytes in the spleen, possibly in the marginal zone, was needed for localization of aggHGG on FDC.…”

Replication of scrapie in spleens of SCID mice follows reconstitution with wild-type mouse bone marrow

“…This led to the suggestion that FDCs could be candidates in the peripheral replication of the agent and this has been sustained by the immunolocalization of the normal host protein, PrP, which has a pivotal role in scrapie cellular pathogenesis . FDCs are radiationresistant (Jaroslov & Nossal, 1966) and not dependent on a high level of replenishment. Their function includes subserving B cell immunity and hence immunological memory (Koscoe et aI., 1992).…”

Reconstruction of lymph follicles in the mouse popliteal lymph node after X-irradiation damage.

“…The stroma of follicles is constituted from follicular dendritic cells that can trap and retain antigen (Nossal et al 1964(Nossal et al , 1968Mitchell and Abbot 1965 ;Hoefsmit 1975 ;Chen et al 1978 ; Klaus et al 1980). It has been reported that X-irradiation causes damage to a certain extent to the morphology of follicular dendritic cells and to the capacity of these cells to retain antigen (Jaroslow and Nossal 1966 ;Williams 1966 ;Nettesheim and Hanna 1969). The present study suggests that in spite of such damage, each persisting stroma of follicles damaged by 600 R X-irradiation may retain the capacity to collect circulating B lymphocytes and reform the lymph follicle.…”