FOR MBBS STUDENTS

1. Rheumatoid Factor & RPR
Dr.P.B.PRAVEENKUMAR
FIRST YEAR POST GRADUATE
DEPARTMENT OF MICROBIOLOGY
THANJAVUR MEDICAL COLLEGE

2. HOW TO APPROACH THIS PRACTICAL
EXERCISE IN EXAM????
• AIM
• PRINCIPLE
• PROCEDURE
• INTERPRETATION

3. RHEUMATOID FACTOR
AIM: This diagnostic reagent kit is used for in-
vitro detection of Rheumatoid factor in
patient serum.

4. PRINCIPLE
SLIDE (LATEX) AGGLUTINATION: RA test antigen
consists of polystyrene latex particles coated
with specially purified human gammaglobulin.
The suspension of coated latex particles
agglutinate visibly when mixed with the serum
containing Rheumatoid factor.

5. PROCEDURE
QUALITATIVE METHOD:
*Bring the reagents and samples to room
temperature
*Put three circles in slide for PC,NC & Test.
*Add one drop of PC,NC & Test in corresponding
circles.
*Add one drop of latex reagent to all three circles.
*Rock the slide to and fro gently for two
minutes(Not beyond 2 minutes) & See for
agglutination.

6. INTERPRETATION OF QUALITATIVE
TEST
COARSE AGGLUTINATION WITHIN ONE
MINUTE
STRONGLY POSITIVE
FINER AGGLUTINATION WITHIN TWO
MINUTES
WEAKLY POSITIVE
SMOOTH SUSPENSION NEGATIVE
NOTE: COARSE AGGLUTINATION = RHEUMATOID FACTOR IS MORE THAN 20 IU/ml. TO
SAY ACCURATELY GO FOR SEMI QUANTITATIVE TEST..........

7. PROCEDURE (cont.)
SEMIQUANTITATIVE METHOD:
*Dilute the specimen serially in the ratio of 1:2,
1:4, 1:8, 1:16, 1:32, 1:64 using normal saline.
*Add one drop of latex reagent in each of these
circle. Mix well with applicator stick.
*Rock the slide gently to and fro for two minutes
and examine for agglutination.

8. INTERPRETATION (cont.) OF
SEMIQUANTITATIVE TEST
Concentration of RF (IU/ml) =
Sensitivity (8 IU/ml) * Titre (Highest dilution)
For example: Agglutination stopped in 1:8 titre
means RF Concentration = 8 * 8  64 IU/ml

9. RAPID PLASMA REAGIN
AIM: This diagnostic test kit is used to detect
reagin antibodies in serum for syphilis.

10. PRINCIPLE
SLIDE FLOCCULATION TEST: The antigen used is
modified cardiolipin antigen in which micro
particulate carbon particles are suspended, in
addition, it contains a balanced quantity of
cholesterol and lecithin. In the presence of
reagin antibodies in serum, clumps or
aggregates appear which can be visualized as
black clumps against white background of the
slide, macroscopically.

11. PROCEDURE
QUALITATIVE TEST:
*Bring all the reagents to room temperature.
*Put three circles in slide for PC,NC & Test.
*Add one drop of PC,NC & Test serum in
corresponding circles.
*Add one drop of RPR reagent to all three circles &
mix with three separate sticks.
*Rock the slide to and fro gently for six minutes(Not
beyond six minutes)

12. INTERPRETATION OF QUALITATIVE
TEST
• CLUMPING OF CARBON PARTICLES –
REACTIVE/POSITIVE
• COMPLETE ABSENCE OF BLACK AGGREGATES
& PRESENCE OF UNIFORM GRAYISH
SUSPENSION – NON REACTIVE/NEGATIVE

13. PROCEDURE (cont.)
SEMIQUANTITATIVE METHOD:
*Dilute the specimen serially in the ratio of 1:2,
1:4, 1:8, 1:16, 1:32, 1:64 using normal saline.
*Add one drop of RPR reagent in each of these
circle. Mix well with applicator stick.
*Rock the slide gently to and fro for six minutes.
*Interpretation – Reciprocal of highest dilution
shows positive

14. THANK YOU