Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Immunization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed1994

[Studies on cell-mediated immunity (CMI) in the glomeruli: immunization with GBM antigen from Masugi nephritis in Wistar-Kyoto rats].

The role of cell-mediated immunity in glomerular injury has been extensively studied, but the precise mechanism remains obscure. This study was undertaken to determine whether the homologous glomerular basement membrane (GBM) combined heterogeneous anti-GBM antibody would induce cell-mediated immunity. Wistar-Kyoto rats were divided into three groups; group I rats were immunized with homologous GBM antigen that was derived from Masugi nephritis and emulsified in complete Freund's adjuvant (CFA); group II rats were immunized with homologous GBM antigen that was derived from normal rats and emulsified in CFA; group III rats were immunized with CFA only. Group I rats demonstrated proteinuria on days 7 and 10 after immunization. Histologically, mesangial cell proliferation and cell infiltration were observed in the glomeruli. No changes in tubulointerstitial tissue. CD4-positive cells, CD8-positive cells and macrophages were found in the glomeruli, and mononuclear cells were found in the glomerular capillary lumen. Group II and Group III rats demonstrated no proteinuria and no histological changes. These findings indicated that the altered GBM obtained antigenicity and induced cell-mediated immunity in the glomeruli.

Animals↗
PubMed1996

The immunization status of Texas children aged 3 to 24 months: results of the 1994 Texas immunization survey.

Texas has no routine system to determine current immunization levels in preschoolers. To determine the current immunization status of Texas children younger than 2 years, the Texas Department of Health commissioned a household survey in 1994. The survey included 4552 in-person interviews with parents or legal guardians of children aged 3 to 24 months. Results showed a statewide up-to-date immunization level of 55%. The younger the children, the more likely they were to be up-to-date. Differences were marked among groups based on geography, race/ethnicity, and use of public assistance. Hispanic children, children enrolled in the Women, Infants, and Children program, and children living in border communities had higher levels of immunizations. Immunization levels were below the statewide average for African-Americans, children on Aid to Families with Dependent Children, and children on Medicaid. Children with no health insurance and children with private insurance had equivalent immunization levels. Although progress appears to have been made in getting children immunized according to recommended schedules, much work remains to be done to reach our state and national goals and to protect our youngest from outbreaks of vaccine-preventable diseases.

Diphtheria-Tetanus-Pertussis Vaccine↗
PubMed1997

Anticarrier immunity suppresses the antibody response to polysaccharide antigens after intranasal immunization with the polysaccharide-protein conjugate.

We have conjugated cholera toxin (CT) B subunit (CTB) to dextran and studied the effect in mice of previous immunization with CT and CTB on the response to dextran after intranasal immunizations with conjugate. Preexisting immunity to CTB was found to inhibit both the lung mucosal response and serum antibody response to dextran, but this effect could be overcome by using a higher dose of conjugate and delaying the conjugate immunization until the CTB antibody titers had declined. The role of anti-CTB antibodies on the mucosal surface was probably to prevent uptake of the conjugate through a mechanism of immune exclusion. Passively transferred serum antibodies against CTB, on the other hand, suppressed both the serum response and the local antibody response against CTB but did not affect the response to dextran after intranasal immunization with conjugate.

Administration, Intranasal↗
PubMed1975

Immune mechanisms in leukemia: suppression of cellular immunity by drugs and x-irradiation.

The relative suppressive effects of x-irradiation (XR), cyclophosphamide (CY), prednisolone (PRD), and methotrexate (MTX) on the primary and secondary cellular immune response of C58/wm mice to syngeneic line Ib transplantable leukemia (Ib cells) were quantified. An LD10 dose of each agent was used for immunosuppression. XR, CY, and PRD were markedly suppressive for the primary immune response if given 24 hr before mice were immunized to Ib cells but less immunosuppressive if given 24 hr later. MTX was only slightly immunosuppressive XR, CY, and PRD also suppressed the secondary immune response if given before but not after antigen. The immunosuppressive effect of these agents was evaluated by defining their median immunosuppressive dose or the median time in days required for mice to recover from graded doses of each immunosuppressive agent. For example, the median recovery time from an LD10 of XR, CY, and PRD was 29.3, 19.7, and 3.7 days, respectively. Immunologic competence remaining after XR or drug treatment was quantified in terms of the LD50 dose of Ib cells required to kill recipient mice. For XR, CY, PRD, and MTX it was 10(6.16), 10(2.15), 10(6.90) and greater than 10(7.0) viable Ib cells, respectively. The overall results provided evidence that the primary and secondary cellular immune responses to a weak syngeneic tumor antigen were resistant to immunosuppression once they were initiated. There was a good correlation between the relative immunosuppressive effect of the test agents and the amount that they reduced the number of immune spleen cells. The agents also impaired the immunocompetence of individual spleen cells. Mechanisms by which XR or drugs might exert their immunosuppressive effects were discussed.

Animals↗
PubMed1992

Measles herd immunity. The association of attack rates with immunization rates in preschool children.

OBJECTIVE: To examine the association between incidence of measles and immunization coverage among preschool-age children. DESIGN: An ecological study in which measles incidence was compared with immunization coverage among census tracts. The independent effects of race and population density were controlled for. SETTING: A recent measles outbreak in Milwaukee, Wis. Immunization coverage data were estimated from a retrospective, school-based survey of Milwaukee grade school students. PATIENTS: One thousand eleven persons (less than or equal to 17 years) who had confirmed measles from September 1989 through June 1990. MAIN OUTCOME MEASURES: Confirmed measles cases grouped by census tract, corresponding census tract preoutbreak immunization coverage, racial breakdown, and population density. RESULTS: Census tracts stratified into four levels, with mean immunization rates of 50.4%, 60.2%, 69.9%, and 81.0%, had respective median attack rates of 11.6, 5.0, 1.7, and 0.0 cases per 1000 persons (P less than .01). The association between immunization coverage and measles attack rate remained significant even after controlling for race and population density. CONCLUSIONS: Modest improvements in low levels of immunization coverage among 2-year-olds confer substantial protection against measles outbreaks. Coverage of 80% or less may be sufficient to prevent sustained measles outbreaks in an urban community.

Adolescent↗
PubMed1996

Mechanisms of immune suppression in patients with head and neck cancer: influence on the immune infiltrate of the cancer.

Freshly excised human head and neck cancers (219 primary cancers; 64 metastatic lymph node cancers) were analyzed for the immune inhibitory mediators released from the cancer tissues and the immune infiltrate within the tumor. Significant levels of the immune inhibitory mediators transforming growth factor-beta (TGF-beta), prostaglandin E2 (PGE2) and interleukin-10 (IL-10) were released from these cancers. Also released was granulocyte-macrophage colony-stimulating factor (GM-CSF), whose secretion was associated with an intratumoral presence of CD34+ cells. We have previously shown that CD34+ cells within human head and neck cancers are immune inhibitory granulocyte-macrophage progenitor cells. The presence of TGF-beta, PGE2 and IL-10 was associated with a reduced content of CD8+ T-cells within the cancers. The CD4+ cell content appeared to be less affected by these immune inhibitory mediators. Instead, parameters indicative of CD4+ cell function (p55 IL-2 receptor expression, release of IL-2 and IFN-gamma) were diminished in cancers that released higher levels of TGF-beta, IL-10 and GM-CSF and had a higher CD34+ cell content. Furthermore, metastatic cancers released higher levels of the soluble immune inhibitory mediators and lower levels of IFN-gamma and IL-2 than did primary cancers, although CD34+ cells were similarly present in both primary and metastatic cancers. Our results show that human head and neck cancers have a multiplicity of non-mutually exclusive mechanisms of immune suppression that are most prominently associated with reduced CD8+ cell influx and reduced influx and altered function of intratumoral CD4+ cells.

CD4-Positive T-Lymphocytes↗
PubMed2002

Systemic and mucosal immune responses in mice after rectal and vaginal immunization with HIV-DNA vaccine.

We examined the feasibility of inducing local and systemic human immunodeficiency virus (HIV)-specific immune responses by rectal and vaginal application of an HIV-DNA vaccine. Mice were immunized with an HIV-DNA vaccine preparation via a rectal or vaginal route. After several applications, HIV-specific antibodies were detected in sera, fecal extract solutions, and vaginal washes, and these antibodies were potent in inhibiting the syncytium formation of a CD4-positive human T cell line by a cell line capable of inducing HIV-1 infection. Spleen cells from rectally and vaginally immunized mice showed antigen-mediated IFN-gamma-inducing activity. In addition, with rectal immunization, mononuclear cells from both the spleen and the regional lymph nodes of the rectal region were found to be potent at inducing a cytotoxic T lymphocyte response. These humoral and cell-mediated immune responses were enhanced by augmenting the vaccine with granulocyte-macrophage colony-stimulating factor-expressing plasmids or IL-12-expressing plasmid. Our results demonstrated that both rectal and vaginal immunization could induce systemic and mucosal immunity and that these responses were enhanced by the addition of the above cytokine-expressing plasmids.

AIDS Vaccines↗
PubMed1995

DNA-mediated immunization and the energetic immune response to hepatitis B surface antigen.

A new and unusual approach for evoking an immune response has recently been introduced--that of DNA-based immunization. Purified plasmid DNA, containing protein coding sequences and the necessary regulatory elements to express them, can be introduced into tissues of the organism by means of a parenteral injection or by particle bombardment. The number of cells transfected and the amount of protein produced is sufficient to produce a remarkably strong and broad-based immune response to a wide variety of foreign proteins. The absence of an exogenous infectious agent or immunogen results in the abrupt appearance of a foreign protein within the normal cells of an immunologically mature and healthy animal and provokes an energetic and efficient reaction to this form of antigen presentation. This review summarizes the results obtained with the various experimental models that have been described to date and considers in greater depth the immune response to the surface antigen of the human hepatitis B virus that has been achieved using DNA-based immunization. Several issues are addressed in a prospective manner in order to anticipate some future developments and to point out topics likely to be pertinent to this field. DNA-mediated induction of immune responses may soon be applied as a form of therapeutic treatment. Although this method may constitute a revolution for vaccination, many issues must first be dealt with, especially concerning the safety of using DNA as an immunizing molecule.

Animals↗
PubMed1993

The immune system response during development and progression of carcinogen-induced rat mammary tumors: prevention of tumor growth and restoration of immune system responsiveness by thymopentin.

A detailed analysis of the immune system response has been performed during the development and progression of dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumors. For this aim, a number of immune parameters (thymocyte and splenocyte proliferative response to T-dependent mitogens, antibody production, lymphocyte subset phenotyping, interleukin 2 receptor expression in resting and activated lymphocytes, thymus morphology and morphometry), were correlated with tumor appearance and growth at different (-7, 0, +15, +30, +60, +90, and +120 days) time intervals after intragastric administration of DMBA, in the absence or the presence of a concomitant treatment with the thymic pentapeptide thymopentin (TP5). A profound and time-dependent immunosuppression characterized the treatment with the carcinogen. Both cell-mediated and humoral immune responses showed a 50% inhibition 2 weeks after DMBA administration, with a peak after 30 days, followed by a plateau until 120 days of observation. The mechanism responsible for reduced ability of thymocytes and splenocytes to respond to both Con-A and PHA was explained by the significant inhibition of one of the key steps of T cell activation, namely the expression of IL-2 receptor in lymphocytes from DMBA-treated animals. The flow cytometric analysis of lymphocyte subpopulations revealed an important reduction in the overall populations of thymocytes and splenocytes. At the thymus gland level, a dramatic reduction of double positive CD4+CD8+ and a decrease of CD4+CD8- and CD4-CD8+ were observed, together with a marked atrophy of the thymic cortex, and impairment of the thymic microenvironment. One hundred and twenty days after DMBA administration, approximately 60 to 70% of the animals developed tumors with a mean tumor surface area of 2.88 +/- 0.86 cm2, and a number of 2.44 +/- 1.0. Treatment with TP5 (100 ng/animal, three times a week, starting a week before DMBA), produced specific effects on different immune compartments and tumoral growth, characterized by a significant reversal of immune depression with a stimulatory effect measured on lymphoproliferative assays, lymphocyte subset distribution, and IL-2 receptor expression. Moreover, thymic atrophy was almost completely prevented in TP5 treated animals. Of major interest, a significant delay in the appearance and growth of tumors was observed in TP5 treated rats. When DMBA-treated animals were followed for the entire observation period (0-120 days) and the immune responsiveness correlated according to tumor progression, stability, or regression, a positive correlation was calculated between the degree of immune system depression and the individual rate of tumor growth; in TP5-treated rats the majority of the tumors were static or regressing tumors.(ABSTRACT TRUNCATED AT 400 WORDS)

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1986

Adoptive transfer of immunity against virulent Semliki Forest virus with immune spleen cells from mice infected with avirulent Semliki Forest virus.

This paper describes the minimal requirements to protect mice adoptively against challenge with virulent Semliki Forest virus (SFV). Early immune serum, from donor mice infected with an avirulent strain of SFV, contained mainly neutralizing IgM immunoglobulins. More of these antibodies (1.80 PND50 vs 0.06 PND50) were needed to protect recipient mice against intraperitoneal challenge (10 LD50 of SFV) than against subcutaneous challenge (7 LD50). Adoptive transfer experiments indicated that a minimum of 3 X 10(7) six-day immune spleen cells were also able to protect recipient mice against intraperitoneal challenge with 10 LD50 of SFV. Treatment of these donor cells with cytotoxic antisera and complement revealed both T- and B-lymphocytes were required for optimum adoptive immunity. Surviving recipients of either immune serum or immune spleen cells developed significantly less neutralizing antibodies than control mice. The lower antibody titres in protected mice might be related to either immune serum or immune spleen cell mediated restriction of virus replication; meaning a reduced antigenic stimulus in these mice compared to control mice.

Animals↗
PubMed2005

Immune responses during pregnancy in heifers naturally infected with Neospora caninum with and without immunization.

This study was designed to identify changes in parasite-specific immune responses that occur during vertical transmission of Neospora caninum and can be used as indicators of parasite reactivation in naturally infected heifers. Ten heifers were unimmunized and 11 immunized with killed tachyzoites. One unimmunized heifer, which aborted at week 19 of gestation, had an increase in parasite-specific antibodies, mainly IgG(2), from week 15 to week 19 and a concomitant decline in parasite-specific cell-mediated immune (CMI) responses. Eight unimmunized heifers, which had live full-term congenitally infected calves, had an increase in antibodies, mainly IgG(2), from week 21 onwards. All immunized heifers delivered live full-term congenitally infected calves, and had a bimodal increase in antibodies; primarily IgG(1) following immunization and predominantly IgG(2) from week 17 onwards. Immunized heifers had significantly greater overall mean humoral and CMI responses than unimmunized heifers. Nine uninfected control heifers and their calves were seronegative. These results indicate that reactivation of a latent infection occurred in the naturally infected heifers, regardless of their immunization status, and was associated with increased parasite-specific antibodies, mainly IgG(2).

Abortion, Veterinary↗
PubMed1987

Secretory immunity induced in catfish, Ictalurus punctatus, following bath immunization.

Individual adult channel catfish were immunized by immersion in an antigen bath containing dinitrophenylated-horse serum albumin. Anti-DNP hemagglutination titers of serum and cutaneous mucus were determined following both primary and secondary bath immunization. The results showed that five of the six fish had a cutaneous mucosal anti-DNP titer following the bath immunizations. In contrast, only one of the six catfish was shown to have any demonstrable change in its serum anti-DNP titer following the bath immunizations. The mucous anti-DNP hemagglutinin was shown to be antibody (Ab). The affinity-purified mucous Ab was found to have the same complex tetrameric architecture as well as the same molecular weight heavy and light chains as serum anti-DNP Ab. Histological studies showed that the catfish epidermis was richly vascularized. Within the epidermis there were numerous lymphocytes which were predominantly associated with the basal layer. These studies indicate that the secretory immune system of catfish can be stimulated by external antigens. Secondly, these studies show that bath immunization can differentially effect the relative antibody response of the catfish secretory and systemic immune systems.

Animals↗
PubMed1992

Humoral and cell-mediated immunity in mice after immunization with live oral vaccines of Salmonella typhimurium: auxotrophic mutants with two attenuating markers.

Persistence and clearance of the vaccinal strains, humoral and cell-mediated immune response and protective immunity were assessed in ICR mice, immunized intraperitoneally or intragastrically with double-marker auxotrophic mutants of Salmonella typhimurium strains 1771 and 3334 (his-pur-). Strain 3334 possesses in addition the antiepidemic Hst (high sensitivity to tensides) marker which confers decreased survival in the gut and environment. The results showed that the strains are not overattenuated. They revealed preserved multiplication capacity, established carrier state for 28-30 days and induced humoral and cell-mediated immunity as measured by passive haemolysis and microagglutination or footpad swelling tests, respectively. The immune response was determined by biological features of the strains. Strain 1771 induced synthesis of O- and H-antibodies 7-11 days earlier than strain 3334. Footpad reactions appeared 3-4 days after immunization and a week before the serum antibodies. Cell-mediated immunity showed clear correlation with the protection against challenge with a virulent strain. The present results suggest that the double-marker auxotrophic mutants of S. typhimurium might prove very useful in the development of a live vaccine in further studies on livestock.

Administration, Oral↗
PubMed1993

Immune response of chimpanzees after immunization with the inactivated whole immunodeficiency virus (HIV-1), three different adjuvants and challenge.

Purified whole virus preparations of HIV-1 were produced from supernatants of infected cells and concentrated 5000-fold. After inactivation with formaldehyde, the concentrates were combined with one of three different adjuvants, and used to immunize three groups of three chimpanzees each. The chimpanzees were monitored for HIV-specific humoral and cellular immune responses by ELISA, immunoblot, virus neutralization, delayed-type hypersensitivity, lymphocyte proliferation and antibody-dependent cell-mediated cytotoxicity. Weak and inconsistent responses were observed in animals that received HIV-1 formulated with alum as adjuvant, whereas HIV-1 formulated with incomplete Freund's adjuvant or an experimental adjuvant (BWZL) induced good humoral and cellular immune responses to the virus. The three animals that received HIV-1 with the BWZL adjuvant generated overall the best immune responses; therefore, 2 weeks after the sixth immunization these animals were challenged with infectious HIV-1. Despite the presence of good humoral and cell-mediated immunity, all three immunized animals and a control animal became infected within 4 weeks, as evidenced by repeated isolation of HIV-1 from peripheral blood mononuclear cells and anamnestic antibody responses. The new experimental adjuvant has to be further investigated in other vaccine trials and different animal models.

AIDS Vaccines↗
PubMed2005

Immunization coverage among Hispanic ancestry, 2003 National Immunization Survey.

BACKGROUND: The Hispanic population is increasing and heterogeneous (Hispanic refers to persons of Spanish, Hispanic, or Latino descent). The objective was to examine immunization rates among Hispanic ancestry for the 4:3:1:3:3 series (> or = 4 doses diphtheria, tetanus toxoids, and pertussis vaccine; > or = 3 doses poliovirus vaccine; > or = 1 doses measles-containing vaccine; > or = 3 doses Haemophilus influenzae type b vaccine; and > or = 3 doses hepatitis B vaccine). METHODS: The National Immunization Survey measures immunization coverage among 19- to 35-month-old U.S. children. Coverage was compared from combined 2001-2003 data among Hispanics and non-Hispanic whites using t-tests, and among Hispanic ancestry using a chi-square test. Hispanics were categorized as Mexican, Mexican American, Central American, South American, Puerto Rican, Cuban, Spanish Caribbean (primarily Dominican Republic), other, and multiple ancestry. RESULTS: Children of Hispanic ancestry increased from 21% in 1999 to 25% in 2003. These Hispanic children were less well immunized than non-Hispanic whites (77.0%, +/-2.1% [95% confidence interval] compared to 82.5%, +/-1.1% (95% CI) > in 2003). Immunization coverage did not vary significantly among Hispanics of varying ancestries (p=0.26); however, there was substantial geographic variability. In some areas, immunization coverage among Hispanics was significantly higher than non-Hispanic whites. CONCLUSIONS: Hispanic children were less well immunized than non-Hispanic whites; however, coverage varied notably by geographic area. Although a chi-square test found no significant differences in coverage among Hispanic ancestries, the range of coverage, 79.2%, +/-5.1% for Cuban Americans to 72.1%, +/-2.4% for Mexican descent, may suggest a need for improved and more localized monitoring among Hispanic communities.

Child, Preschool↗
PubMed2004

Species-specific immune response to immunization with human versus rodent A beta peptide.

Amyloid beta (A beta) immunization of amyloid precursor protein (APP)-transgenic (tg) mice with human A beta induces humoral immunity, however, the immune response to endogenous rodent A beta is unknown. Fourteen-month J20 APP-tg mice and non-tg littermates were immunized subcutaneously followed by chronic intranasal boosting with human or rodent A beta peptide and adjuvant LT(R192G). Rodent A beta-immunized APP-tg mice had anti-rodent A beta antibody levels of 257.8 micrograms/ml and those immunized with human A beta had anti-human A beta antibodies of 120.8 micrograms/ml. Non-tg littermates had anti-rodent and anti-human A beta antibody concentrations of 98.8 and 231.1 microgram/ml, respectively. Inter-species cross-reactivity was minimal. Anti-human A beta antibodies were predominately IgG1 and IgG2b, while anti-rodent A beta antibodies were equally IgG1, IgG2a, and IgG2b. Anti-human A beta antibodies recognized an epitope within human A beta1-9. Anti-rodent A beta antibodies did not stain Alzheimer's disease (AD) plaques but bound some plaques in APP-tg mice. Splenocytes proliferated modestly to their respective antigen and secreted low levels of IL-2 and IFN-gamma. Therefore, immunizing APP-tg and non-tg mice with rodent A beta resulted in a species-specific humoral response with modest T cell reactivity.

Alzheimer Disease↗
PubMed2006

Transcutaneous immunization with inactivated influenza virus induces protective immune responses.

The recent outbreaks of highly pathogenic avian influenza in Asia and spread of the disease worldwide highlight the need to redefine conventional immunization approaches and establish effective mass vaccination strategies to face global pandemics. Transcutaneous immunization (TCI) is a novel route for vaccination, which uses the topical application of vaccine antigens on the skin. In this study, we investigated the potential of TCI using inactivated whole influenza virus. We found that TCI with whole inactivated influenza virus induced influenza virus-specific antibodies with hemagglutination inhibition and neutralizing activities as well as cellular immune responses, even without an adjuvant, and conferred protective immunity to virus challenge. Co-administration with cholera toxin (CT), a potent adjuvant for TCI, significantly enhanced immune responses against the influenza virus antigen. To enhance penetration of the skin barrier to the particulate influenza viral antigens, we tested the effects of the potential penetration enhancers/immunomodulators oleic acid (OA) and retinoic acid (RA). Pretreatment of mouse skin with OA elicited increased levels of influenza virus-specific binding and neutralizing antibodies to levels equivalent to those induced by intranasal immunization with inactivated influenza virus. OA and RA treatments differentially affected the pattern of cytokine production upon stimulation with influenza viral antigen and provided enhanced protection. These results reveal a promising perspective for the application of transcutaneous immunization to prevent influenza epidemics as well as a range of other infectious diseases.

Administration, Cutaneous↗
PubMed1999

Analysis of cloned Fvs from a phage display library indicates that DNA immunization can mimic antibody response generated by cell immunizations.

BACKGROUND: Generation and cloning of antibodies against cell surface antigens can be simplified by combining DNA immunization which enables generation of antibodies against a protein in its natural configuration without the need for any protein purification step and antibody phage display which due to its immense screening power and physical coupling between the phenotype and genotype of antibodies simplifies the cloning of antibody genes. OBJECTIVES: Since DNA immunization is expected to elicit antibodies against a protein in its natural configuration, we wanted to see if it can mimic the antibody response generated by cell immunization. STUDY DESIGN: A phage display library made from splenic mRNA of a mouse immunized with mesothelin cDNA was panned on mesothelin-positive cells. The single-chain Fvs (scFvs) selected were then analyzed. RESULTS: We obtained several anti-mesothelin scFvs. One of these Fvs is almost identical to the Fv of a monoclonal antibody that was previously obtained from a hybridoma in which the mice were immunized with a mesothelin-positive ovarian cancer cell line. Another Fv was found to be specific for mesothelin present on human cells. CONCLUSION: Our results indicate that an antibody phage display library made from spleens of DNA-immunized mice is a rapid and efficient alternative to cell immunization for obtaining antibodies against different epitopes of a membrane antigen that is very difficult to purify in a native form.

3T3 Cells↗