Proinflammatory T cell polarization is already present in patients with early knee osteoarthritis

Table 2 CD4⁺ T cell infiltration in the peripheral blood (PB) and joint-derived samples (SF, SM)

	PB	SF	SM	p values
	PB	SF	SM	PB:SF	PB:SM	SF:SM
n	18	18	18
Sample volume/weight (PB, SF: ml; SM: g)	7.6 ± 0.4 (6.6–8.5)	4.2 ± 1.1 (1.8–6.5)	0.22 ± 0.03 (0.15–0.28)	n.a.	n.a.	n.a.
CD3⁺ MACS-isolated T lymphocytes of total living cells	92.2 (88.2–93.8)	46.8 (32.0–62.3)	12.3 (4.9–21.3)	0.0002***	0.0002***	0.0004***
Cell count of CD3⁺ MACS-isolated T lymphocytes	39.9 × 10⁵ ± 6 × 10⁵ (26 × 10⁵–53 × 10⁵)	0.96 × 10⁵ ± 0.3 × 10⁵ (0.25 × 10⁵–1.6 × 10⁵)	0.08 × 10⁵ ± 0.02 × 10⁵ (0.03 × 10⁵–1.3 × 10⁵)	n.a.	n.a.	n.a.
CD4⁺ T cells % of T lymphocytes	71.2 (60.6–81.1)	38.8 (27.5–49.4)	44.3 (36.5–49.4)	0.0002***	0.0002***	0.472
Cell count of T lymphocytes per sample volume/weight (PB/SF: cells/μl; SM: cells/mg	558.1 ± 88.5 (369.4–746.8)	51.3 ± 21.3 (7–95.5)	42.5 ± 12.7 (16.2–68.8)	n.a.	n.a.	n.a.

Number and mean volume/weight ± standard deviation (CI) of acquired and analyzed samples are given. Further, percentage rate and mean cell count ± standard deviation (CI) of CD3⁺ MACS-isolated T lymphocytes and the percentage of CD4⁺ MACS-isolated T lymphocytes in the peripheral blood (PB), synovial fluid (SF), and synovial membrane (SM) of early OA patients are shown. The cell count was taken in relation to the acquired sample volume/weight to illustrate the amount of inflammatory T cells in the different tissues. In brief, mononuclear cells were isolated from PB, SF, and SM by density gradient centrifugation. Further, T lymphocytes were isolated by CD3⁺ magnetic cell separation (MACS), stained with monoclonal antibodies (mAb) against CD4, and analyzed by flow cytometry. Data is shown as median (IQR), if not stated otherwise. Significant differences are marked with asterisks: *p < 0.05; **p < 0.01; ***p < 0.001
n.a. not applicable, MACS magnetic activated cell sorting, IQR interquartile range

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