Distribution of T-lymphocyte subsets in porcine lymphoid tissues

The distribution of the functional subsets of porcine T cells, the
cytolytic/suppressor (Tc/s) and the helper/inducer (Th/i) cells was
studied in cryostat sections of thymus, lymph nodes, tonsils,
Peyer's patches, spleen and liver using the indirect
immunoperoxidase technique. Three murine monoclonal antibodies
(mAb) were used. The mAb 8/1 reacts with an antigen present on all
T cells and on cells of the myeloid lineage; the antigen has not
yet been characterized biochemically. The mAb 295/33 (anti-T8)
binds to the porcine T8 antigen and defines the Tc/s subset, while
mAb PT-4 (anti-T4) detects the porcine T4 antigen and defines the
Th/i subset. Practically all thymocytes were stained by mAb 8/1.
The majority of cortical thymocytes apparently co-expressed T8 and
T4, whereas distinct fractions of medullary cells were labelled by
either anti-T8 or anti-T4. In peripheral lymphoid organs all three
mAb reacted with cells in the thymus-dependent areas and with cells
scattered in the lymphoid follicles. In lymph nodes, tonsils and
Peyer's patches, anti-T8 and anti-T4 each labelled approximately
half of the cells stained by mAb 8/1. In the periarteriolar
lymphoid sheath of the spleen, anti-T4 labelled more cells than did
anti-T8. The reactivity of mAb 8/1 with the Kupffer cells of the
liver demonstrated the expression of the 8/1 antigen on cells of
the monocyte lineage. The T8 and T4 antigens could not be detected
in acetone-fixed and paraffin-embedded sections, while the antigen
recognized by mAb 8/1 remained preserved. Altogether, despite an
inverted microanatomical structure of porcine lymph nodes, the
frequency and distribution of T8+ and T4+ cells in thymus-dependent
areas proved to be similar to those found in other species.