B and T cells in a cat with thymic lymphosarcoma

A method of purifying feline T lymphocytes from peripheral blood using the plant lectin from Pisum sativum

The binding properties of several plant lectins on feline peripheral blood lymphocytes (PBL) were examined by flow cytometry to reveal if any could serve as probes for identifying specific lymphocyte subclasses. Most of the lectins bound > or = 90% of PBL in a uniform manner. The exceptions were the lectins from Glycine max, Phaseolus limensis, and Dolichos biflorus, which bound only a proportion of the PBL. The differential binding of the lectins to lymphocyte subclasses was examined by comparing the staining of control PBL to T cell-depleted PBL. The lectins from Pisum sativum, Lens culinaris, succinylated Triticum vulgaris, and Dolichos biflorus stained T-depleted PBL more brightly than control PBL. Extensive cytofluorometric analyses of the binding properties of Pisum sativum agglutinin (PSA) on feline PBL and mesenteric lymph node cells indicated that feline B lymphocytes express more higher affinity surface receptors for PSA than do T lymphocytes. The higher affinity binding of PSA to B lymphocytes was further demonstrated by PSA-mediated cellular affinity chromatography. With this procedure it was possible to deplete PBL of B lymphocytes and to obtain pure populations of feline T lymphocytes.

Two populations of guinea pig erythrocyte-rosetting cells in the cat: evidence for their T-helper function in mitogen-induced synthesis of Ig and interleukin-2

Studies in our laboratory have shown that T-helper (T-H) and T-suppressor (T-S) cells in cat peripheral blood leukocytes (PBL) rosette with guinea pig (GP) and gerbil (G) erythrocytes (E), respectively. Removal of GE-rosetting cells leads to an enhanced (two- to threefold) synthesis of Ig in a pokeweed mitogen (PWM)-driven system as measured by plaque-forming cells (PFC) to protein A-coated sheep RBC, while depletion of GPE-rosetting cells yields a PFC response only 10-15% of the control. Surprisingly, removal of both GE- and GPE-rosetting cells gave a response equivalent to 40-100% of the control PBL. Analysis of the mixed GE/GPE rosette depleted cultures revealed the reappearance of GPE- but not GE-rosetting cells, reaching maximum values within 12-18 hr after in vitro culture. Cultures of control PBL and those following the mixed rosette depletion showed two populations of GPE-rosetting cells; the GPE-1 cells, present on Day 0 before culture, and the GPE-2 cells, those appearing on Day 1. Addition of cycloheximide prevented development of the GPE receptor while colchicine and mitomycin C were without effect. The development of PFC after the mixed GE/GPE rosette depletion was interpreted as being due to the GPE-2 cells functioning as T-H cells in the absence of any T-S (GE-rosetting) cells. This thesis was supported by showing a marked decrease in the PWM-induced Ig response when both the GPE-1 and GPE-2 populations were removed on Day 1. Additional evidence for functional T-H cells in the GPE-rosetting population was obtained by analyzing interleukin-2 (IL-2) production. Removal of the GPE-rosetting cells (GPE-1 and/or GPE-2) from PBL led to a marked decrease in Con A-induced IL-2 synthesis while removal of the GE-rosetting cells yielded a normal or slightly greater than normal response.

Sugar competition assays reveal high affinity receptors for Erythrina cristigalli lectin on feline monocytes

An examination of fluorescein-labelled Erythrina cristigalli lectin (FITC-ECL) staining on feline mononuclear cells (MNC) using fluorescent microscopy and a novel sugar titration competition assay revealed that monocytes (MO) were stained brighter by FITC-ECL than were lymphocytes (LYM). When MNC were stained with FITC-ECL in the presence of 400 mM or greater D-galactose, analysis by flow cytometry revealed continued MO staining while LYM were negative. MO expressed a larger quantity of carbohydrate receptors (CHO-R) for ECL than did LYM. The CHO-R expressed on MO were mostly protease-insensitive and uncapped by sialic acid residues. All of the CHO-R on LYM were protease-sensitive and many were capped by sialic acid residues. A combined labelling of MNC for non-specific esterase staining, latex bead ingestion and FITC-ECL staining in the presence of 400 mM D-galactose confirmed that FITC-ECL specifically stains MO in the presence of high sugar competitor concentrations.

The management of feline lymphosarcoma

Lymphoma may occur in almost any site, in a cat of any age, in either a FeLV-infected or uninfected animal. As the most common tumor type found in this species, LSA should be included in the differential diagnosis for virtually any clinical problem in any body system. For the unusual forms of this malignancy, just as for the more common types, the prognosis and response to cytotoxic therapy is generally based on the pretreatment volume and location of the tumor, as well as on the overall status of the cat. Dramatic differences have been noted in the sensitivities of some of the various forms of LSA to conventional chemotherapy. Recognizing these differences and managing our patients and their owners accordingly should make the treatment of this disease far more rewarding.

An immunological classification of ovine lymphomas

Sporadic ovine lymphoma cells were identified as T or B lymphocytes with a T cell-specific antiserum or by detecting surface immunoglobulin. Lymphomas were classified as being of T or B cell origin if 60 per cent, or more, of the cells were of the respective type. Of 16 lymphomas, 6 were T cell and 6 were B cell derived. In one lymphoma more than 60 per cent of the cells were identified as both T and B cells. In the other 3 lymphomas neither T nor B cells reached this value; 2 of these had negligible T and B cell numbers and were classified as null cell lymphomas. A relationship was seen between the immunological and anatomical classifications of the lymphomas in that all the T cell lymphomas were of multicentric distribution while 4 of the 6 B cell neoplasms were confined to the alimentary tract and its associated lymphoid tissue. In contrast, there was no relationship between the immunological and histological classifications of the lymphomas.