Differences In Immune Cell Composition And Response Between Spontaneously Hypertensive Bph/2 Mice And Normotensive Bpn/3 Mice

There is considerable evidence for a role for the immune system in different animal models of hypertension. However, whether there are differences in the immune systems of Bph/2 spontaneously hypertensive mice and Bpn/3 normotensive mice is not known. To address this, we characterized the immune composition and response of male Bph/2 and Bpn/3 mice. Bph/2 mice had significantly lower body weight compared to Bpn/3 mice (Bpn: 32.0 ± 0.5 g; Bph: 23.0 ± 0.5 g) with a proportionately lower spleen weight (Bpn: 70.1 ± 9.8 mg; Bph: 48.6 ± 2.1 mg). As expected, Bph/2 mice had higher blood pressure than Bpn/3 mice. Bph/2 mice also had a higher percentage of CD4 T cells in brachial lymph nodes compared to Bpn/3 mice (Bpn: 48.0 ± 0.57, Bph: 58.6 ± 1.94) and a lower percentage of CD8 T cells (Bpn: 46.4 ± 1.07, Bph: 38.9 ± 1.84), causing an increased CD4:CD8 T cell ratio in Bph/2 mice (Bpn: 1.04 ± 0.03, Bph: 1.53 ± 0.12). This trend was also observed in inguinal lymph nodes, but not in spleens or mesenteric lymph nodes. There were also differences in the response of anti-CD3/anti-CD28-activated splenocytes. Specifically, IFNγ secretion was markedly lower in splenic T cells from Bph/2 mice compared to those from Bpn/3 mice 24 h after activation (Bpn: 4902 ± 1532 pg/ml, Bph/2: 921 ± 462 pg/ml). Similarly, IL-2 (Bpn: 3960 ± 1070 pg/ml; Bph: 1121 ± 247 pg/ml), IL-6 (Bpn: 297 ± 94 pg/ml, Bph: 64 ± 15 pg/ml) and TNFα (Bpn: 170 ± 33 pg/ml; Bph: 59 ± 15 pg/ml) induction was also lower in T cells from Bph/2 mice. Interestingly, we also found that Bpn/3 mice do not express the NK cell marker, NK1.1. Taken together, the data suggest significant differences in immune composition and response between Bph/2 and Bpn/3 mice and indicate a need to further evaluate the role of the immune system in the development of hypertension in this model.