Evaluation of antibodies reactive with porcine lymphocytes and lymphoma cells in formalin-fixed, paraffin-embedded, antigen-retrieved tissue sections

To determine whether antibodies raised against human or porcine lymphocytes are reactive with porcine lymphocytes and lymphoma cells in formalin-fixed, paraffin-embedded, antigen-retrieved tissue sections, and to determine the conditions suitable for antigen retrieval.

We evaluated reactivities of 27 anti-lymphocyte antibodies with porcine tissue sections, including those of lymphomas, treated with 11 antigen-retrieval methods.

Swine.

We used 19 anti-human and 8 anti-porcine lymphocyte antibodies. For antigen retrieval, we tested 11 methods: heating with 6 soaking solutions in a microwave oven, heating with 2 commercially available soaking solutions in a water bath, and enzyme digestion with 3 proteases. After these treatments, sections were immunostained along with untreated sections.

Of 27 anti-lymphocyte antibodies tested, CDw75 (clone LN-1), CD79 alpha (mb-1, clone HM57),CD79 beta (B29, clone B29/123), HLA-DR (clone TAL 1B5), and polyclonal CD3 were strongly reactive with porcine lymphoid tissues, including lymphomas, when sections were deparaffinized and heated in 0.1M Tris-HCl buffer (pH 8.0) in a microwave oven or with antigen-retrieval solution in a water bath. All patterns of positive staining were essentially the same as those previously described in human beings.

These 5 antibodies, with the antigen retrieval sequences, are helpful in identifying, distinguishing, and characterizing lymphocyte subsets in archival sections of normal and pathologic porcine lymphoid tissues including lymphomas. In addition, our findings indicated that antigen retrieval by microwave heating of the sections can appreciably expand the range of antibodies useful in paraffin immunohistochemistry, including those that otherwise work only on sections from frozen tissues or from an antigen-derived species.