CNS microvascular pericytes express macrophage-like function, cell surface integrin alpha M, and macrophage marker ED-2.

CNS pericytes are an integral part of the blood-brain (BBB), but their function is not well understood. We questioned whether primary cultured CNS pericytes have immune potential. Primary cultured pericytes exhibit phagocytic activity when exposed to fluorochrome-conjugated polystyrene beads and antibody-coated zymosan. Maximum phagocytic activity occurred by 3 hr. Pericytes were found to express the macrophage markers ED-2 and the integrin subunit CD11b (alpha M) in culture as well as on isolated microvessels. Pericytes did not express the macrophage marker ED-1. We confirm the heterogeneity of cultured CNS pericytes with regard to expression of alpha-smooth muscle actin. In conclusion, pericytes express macrophage surface antigens and have the ability to perform at least some immune function. CNS pericytes may therefore have a role in neuroimmune networks at the BBB.

The effect of two glucan carboxymethyl derivatives with various substitution degrees on cyclophosphamide immunosuppression in mice.

Carboxymethylglucan (CMG) in two different degrees of substitution of carboxymethyl groups (0.56 and 0.89) was administered to cyclophosphamide (CY) treated (200 mg/kg) C57B1/6 mice in three doses (10, 50, and 100 mg/kg) 24 h after CY. The influence of CMG administration on the cell suppression caused by CY was observed in the subsequent days. The cellularity of spleen, bone marrow and peripheral blood was quantified on days 2, 5, 8, 11, 15, and 21 after CY treatment. CY treated mice developed a significant decrease in peripheral blood cell counts, and spleen and bone marrow cellularity during the initial 5 days, followed by recovery in the next 15 days, with an overshoot reaction in spleen cellularity and erythrocyte levels. The initial cellularity depression and the following recovery was modified by both carboxymethyl derivatives of glucan. Cyclophosphamide treated mice exhibited less pronounced immunosuppression and more rapid hematopoietic recovery when administered with CMG, although this reaction was only of a modest degree. The effects were not dose dependent and the differences between the two glucans were not significant.

Subacute immunotoxicity study of formaldehyde in male rats.

Immune functions were examined in male rats following 28 day oral administration of formaldehyde by gastric tube at dose levels of 0, 20, 40, and 80 mg/kg. Routine parameters examined included hematology, clinical chemistry, and body, thymus, kidney, and liver weights. In addition, cellularity of spleen and lymph nodes, histology of spleen, thymus, lymph nodes, liver kidney, small and large intestines, and histochemistry of spleen and lymph nodes were evaluated. Immune parameters evaluated included serum hemagglutinin antibody response; antibody plaque forming cell response to sheep erythrocytes (lymphocyte-dependent antigen); microbicidal activity of Candida albicans; and phagocytic activity by adhesion of microspheric hydrophilic synthetic particles to leukocyte cell membrane. Body weights were slightly decreased at high dose level (80 mg/kg). The difference was significant when compared to the controls. The lymph node weights were significantly increased in rats receiving formaldehyde. The cellularity of lymphoid organs was not influenced after 28 day exposure to formaldehyde.

The immunoadjuvant effect of soluble glucan derivatives in mice.

We examined the effect of soluble derivatives of yeast glucan on the humoral immune response of various strains of inbred mice after administration of different doses according to various schedules. Glucan was injected i.v. or s.c. in a single dose or repeatedly. The immune response was examined by determining the titres of serum hemagglutinins against sheep erythrocytes (SRBC-Ab). The immunoadjuvant effect of glucan derivatives depends on the inbred strain used, on the dose of glucan, mode and time of administration with respect to antigen injection. The results have shown that the stimulatory effect of glucan derivatives occurred already after a single injection, the optimum dose being 10-20 mg/kg. Intravenous injection was more efficient than the subcutaneous one. In some cases, a slight increase of the spleen mass was observed.

The effect of soluble glucan derivates on spleen colony-forming units in sublethally irradiated mice.

We examined the effects of 5 soluble derivatives of yeast glucan on the formation of exogenous (CFU-S) and endogenous (E-CFU) colony-forming units in the spleens of sublethally irradiated (60Co, 6.5-7.0 Gy) mice of two inbred strains. For the estimation of CFU-S, glucans were administered intravenously either to donors or recipients of spleen cells 24 h prior to irradiation or removal of the spleen. The number of CFU-S was increased when both the donors and recipients were treated with glucan; the highest increase was obtained with glucans S, P and K. All glucan preparations increased significantly also the number of E-CFU even when administered 90 min after irradiation. There exist differences in the response to the stimulatory effect of glucans among individual mouse strains. Thus, for example, the stimulatory effect of glucan KM on the E-CFU number was significantly more pronounced in strain A/Ph than in strain C57Bl/6.