In vitro migration of rat large granular lymphocytes

Natural killer cells and B lymphocytes in L-selectin and Mac-1/LFA-1 knockout mice: marker-dependent, but not cell lineage-dependent changes in the spleen and bone marrow

The majority of B lymphocytes, virgin T lymphocytes and a subpopulation of memory T cells express the addressin, L-selectin. Natural killer (NK) cells in rodents and humans also express L-selectin. We have shown that a similar proportion (40%) of NK cells in mouse spleen also express the integrin, CD18Mac-1, and moreover, that NK cells express both the addressin and the integrin constitutively. It was the aim of the present study to quantify, in knock-out mice deficient for either the L-selectin addressin, or the CD18:Mac-1/LFA-1 integrins, NK cells and B cells in both the spleen and their bone marrow birth site. These cells, in both organs, were immunophenotypically stained with FITC-conjugated anti-NK1.1 (to identify NK cells), and FITC-conjugated anti-mouse B220 (to identify B lymphocytes) and subjected to flow-cytometric analysis using a FACScan equipped with a doublet discrimination module. From the known total organ (spleen, femurs) cellularity, obtained by means of an electronic cell counter, at the time of extraction of each organ, the absolute numbers of NK cells and B lymphocytes from each mouse were obtained. The results revealed that there are significantly more NK cells and B lymphocytes in the spleens of CD18:Mac-1/LFA-1 knockout mice than in control (same strain) mice. Moreover, in L-selectin knockout mice spleens, NK cells and B lymphocytes were elevated by 26.2% and 17.8% respectively. NK cells and B lymphocytes in the bone marrow of the integrin knockout showed no difference from control, however, both cell types in the bone marrow of the L-selectin knockout mice fell to only 3/4 their control levels. Collectively, the results demonstrated that there are organ-specific, but not cell lineage-specific differences in the absolute numbers of NK cells and B lymphocytes, in integrin-deficient (CD18:Mac-1/LFA-1 knockout) mice and addressin-deficient (L-selectin knockout) mice.

Thrombin receptor expression and function in large granular lymphocyte proliferative disorders

It has recently been shown that peripheral blood NK-cells and a fraction of T-cells which co-express CD16 and either CD56 or CD57 express the platelet type thrombin receptor. Large granular lymphocytes exhibit a T- or NK-cell phenotype, and therefore these results raise the possibility that thrombin and its receptor may be involved in the biology of large granular lymphocytes in health and disease. It is difficult, however, to perform functional studies using normal blood as a source of large granular lymphocytes, because the small fraction of large granular lymphocytes cannot be separated from other lymphocytes in numbers sufficient for most in vitro experiments. Therefore patients with large granular lymphocyte proliferative disorders have been screened in order to identify a population of cells enriched in large granular lymphocytes that express the thrombin receptor. Expression of the receptor was analysed in polyclonal and clonal large granular lymphocyte proliferative disorders. Using flow cytometry, it was found that the proportion of thrombin receptor positive large granular lymphocytes varied from 3% to 86%. Northern analysis indicated a high level of expression of mRNA in a clonal expansion of large granular lymphocytes that stained positively for the receptor by flow cytometry. Thrombin was found to act as a chemotactic stimulus for large granular lymphocytes from a polyclonal expansion with high numbers of thrombin receptor positive cells. At an optimal concentration of 10(-9) M the chemotactic response to thrombin was roughly equivalent to that obtained with the potent chemoattractant 1-oleoyl 2-acetyl glycerol. These findings suggest that thrombin may play a role in the recruitment of large granular lymphocytes in sites of inflammation.

Fibronectin facilitates the migration of human natural killer cells

The interaction of lymphocytes with the extracellular matrix plays an important role in the immune defence against tumor cells and virus-infected cells. We have examined the effect of matrix proteins on the migration of large granular lymphocytes (LGL) through 3-microns pores in Nuclepore filters in a Boyden invasion chamber. Fibronectin bound on the filter surface significantly increased (p less than 0.001) the capacity of LGL to migrate, whereas soluble fibronectin did not. In addition, a significantly higher (p less than 0.001) percentage of LGL was capable of migration through fibronectin-coated filters than through untreated filters. With fibronectin-coated filters, a strong enrichment of CD16+ and CD56+CD3- cells with LGL morphology and reduction of CD3+ cells was found among migrating cells when the incubation time was 4 h or less. Later agranular lymphocytes, mainly CD3+ T lymphocytes, also started to migrate. Laminin coating of filters also facilitated migration, and when filters were coated with both fibronectin and laminin the increase in migration was equal to the sum of the increases induced by each protein alone. Interactions between cell surface and the Arg-Gly-Asp (RGD) peptide sequence of many matrix proteins had no role in the LGL migration through untreated filters. However, when filters were coated with either fibronectin or laminin, or with both, peptide containing the RGD sequence reduced migration to the level of untreated filters, whereas an Arg-Gly-Glu control peptide had no effect. Our results show that unstimulated LGL/natural killer cells are capable of rapid migration through matrix-coated porous membranes, and that interactions between cell surface receptors and the RGD sequence of fibronectin and probably laminin are utilized in this process.

Combination treatment using thymosin alpha 1 and interferon after cyclophosphamide is able to cure Lewis lung carcinoma in mice

A combination treatment with thymosin alpha 1 (200 micrograms/kg) for 4 days, followed by a single injection of murine interferon alpha/beta (3 x 10(4) international units/mouse). starting 2 days after cyclophosphamide treatment (200 mg/kg, single injection) demonstrated a dramatic and rapid disappearance of tumor burden in mice bearing Lewis lung carcinoma (3LL) tumor. The effectiveness of this new chemoimmunotherapy protocol was evident even on the long-term survival in a high percentage of animals, and was statistically significant when compared to treatment with the single agents in conjunction with chemotherapy or to chemotherapy itself. The same combination immunotherapy treatment strongly stimulated natural killer activity and cytotoxicity against autologus 3LL tumor cells in 3LL-tumor-bearing mice treated with cyclophosphamide, whereas treatments with each agent singly did not alter or only slightly modified the cytotoxic activity towards Yac-1 or 3LL target cells. Selective depletion with antibodies showed that killer cells stimulated by combination chemoimmunotherapy treatment bear phenotypic characteristics of asialo-GM1-positive cells. A histological study has shown a high number of infiltrating lymphoid cells in the tumors obtained from mice treated with combination chemoimmunotherapy.